What cams to use for a built motor with greddy TT?
05-03-2009, 01:40 PM
#62
For my last build, I think so (though the JWT S7R or C8R for the OP since he is RevUp
). For my new build, I want the C8's. 
I almost went with the GTM 3.8L stroker, which you can rev the **** out of. If I had, the GTM and BC cams would have been the way to go for that build. In that case, I would look at the GTM Stage 2's, the BC Stage 3's and the GTM Stage 3's, depending on how much I was going to drive on the street. Most likely I would have chosen the BC Stage 3's or GTM Stage 3's for that motor.
Since the 4.0L doesn't rev as high, I only need a cam that works to 7500 rpm, in which case I like the JWT cams because of the higher lift they provide. It is the extreme lift, however, that limits how fast you can spin them. The JWT C9's are very nice, but they probably won't be very streetable, especially since the VQ35DE does not have variable phasing on the exhaust valves.
). For my new build, I want the C8's. I almost went with the GTM 3.8L stroker, which you can rev the **** out of. If I had, the GTM and BC cams would have been the way to go for that build. In that case, I would look at the GTM Stage 2's, the BC Stage 3's and the GTM Stage 3's, depending on how much I was going to drive on the street. Most likely I would have chosen the BC Stage 3's or GTM Stage 3's for that motor.
Since the 4.0L doesn't rev as high, I only need a cam that works to 7500 rpm, in which case I like the JWT cams because of the higher lift they provide. It is the extreme lift, however, that limits how fast you can spin them. The JWT C9's are very nice, but they probably won't be very streetable, especially since the VQ35DE does not have variable phasing on the exhaust valves.
Last edited by ttg35fort; 05-03-2009 at 02:46 PM.
05-03-2009, 10:53 PM
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Hmmm...I guess there's many different views with cometic headgaskets....maxima owners who build 3.5 motors that swap into 95-01 maximas don't have any problems. Many are boosted that I can recall.
As for cosworth, I have the 96mm bore on my stock 95.5mm bore on my 2002 vq35fwd build that I swapped in my 99 maxima. I'm boosting this motor as well...just been lazy..I do have all the parts though =] STOCK heads and I'm hitting 7639 @ 120mph 3rd gear pull.
I was looking into a HR head gasket for my 2nd vq35 build with some head work on my maxima since nobody is running them yet. I will def consider them for the Z motor build.
As for cams, the RPM level I want to be pushing over 7500 but no more than 8000. I'm using a rev up short block but non rev up heads.
The valves, I was looking into ferrea or even supertech.
Port and polish: thanks for that info.
Pistons: I was aware about those 9:1 cr pistons that it might be too high. My 2nd choice was picking up Wiseco pistons. Is it necessary to get a .02 ob pistons or stock bore is good enough? I actually purchase the set of used pistons from JetPilot.
As for the other parts, I do have a JWT clutch/flywheel combo. I'm not sure if that clutch would hold that power level but I'll be slapping on the greddy tt kit on my stock motor. I will def look into a better clutch when the motor is built.
I also have a fast intentions 3" TD exhaust.
Where can I buy the wastegate relocation kit???
So running a UTEC is not enough? hmmm...I'll look into the others...
Thanks again for the info!
As for cosworth, I have the 96mm bore on my stock 95.5mm bore on my 2002 vq35fwd build that I swapped in my 99 maxima. I'm boosting this motor as well...just been lazy..I do have all the parts though =] STOCK heads and I'm hitting 7639 @ 120mph 3rd gear pull.
I was looking into a HR head gasket for my 2nd vq35 build with some head work on my maxima since nobody is running them yet. I will def consider them for the Z motor build.
As for cams, the RPM level I want to be pushing over 7500 but no more than 8000. I'm using a rev up short block but non rev up heads.
The valves, I was looking into ferrea or even supertech.
Port and polish: thanks for that info.
Pistons: I was aware about those 9:1 cr pistons that it might be too high. My 2nd choice was picking up Wiseco pistons. Is it necessary to get a .02 ob pistons or stock bore is good enough? I actually purchase the set of used pistons from JetPilot.
As for the other parts, I do have a JWT clutch/flywheel combo. I'm not sure if that clutch would hold that power level but I'll be slapping on the greddy tt kit on my stock motor. I will def look into a better clutch when the motor is built.
I also have a fast intentions 3" TD exhaust.
Where can I buy the wastegate relocation kit???
So running a UTEC is not enough? hmmm...I'll look into the others...
Thanks again for the info!
Headgaskets
Please DO NOT use the Cometic headgasket. There have been problems with these on VQ motors. I can't opine about the Cosworth head gaskets because I don't know anybody who has ran them.
Do yourself a favor and seriously look into using the HR head gaskets or the HKS head gaskets. After speaking in depth about this issue both with Jim Wolf and Sam at GTM, as well as some other forum members, I'm using HR gaskets on my motor. I'll be pushing 700 RWHP on pump gas, and well over that with meth injection on line. FYI, the HR head gaskets cost about $60 - $70, whereas the HKS headgaskets cost $360. Nonetheless, you can't go wrong with HKS headgaskets. I have never heard of one failing on a build without aftermarket sleeves. The problems when aftermarket sleeves were used were due to the sleeves moving, not the gaskets.
Cams
What will your maximum RPM be? That will determine which cam is best for you. MAKE SURE YOU GET REV UP VERSIONS OF THESE CAMS IF YOU ARE USING A REV UP HEAD!!! The VQ35DE cams may not work.
If it will be less that 7500 rpm, (Scratch the C2's, SmallTuner reminded me, in a very polite way I might add, that you are using RevUp Heads). Look at the JWT S7R's and C8R's. You must use the JWT springs with these. They are harmonically balanced for the JWT cam profiles. I'll post their specifications in the previous page. Edit: After posting their respective specifications, I see that they both have minimum overlap. Hence, I would go with the C8Rs.
If you will be reving over 7500 RPM, BC or GTM cams. However, on the Brian Crower site, I did not see any RevUp cams listed. GTM has Stage 1, Stage 2 and Stage 3 cams for the Rev Up motor. So far, the specifications look the same as the non-RevUp motors. For high RPM use, I believe the GTM cams are the ticket.
Valves
The power level is not a problem for the stock valves, but you might want to check to see what RPM they are good to. If the conclusion is that they aren't good for the RPM you will be pushing and you need aftermarket valves, you cannot go wrong with Ferrea valves. I'm sure there are other good valves out there too, but stay away from BC valves. I have heard of them breaking when pushed hard.
Port and Polishing
As far as port and polishing, I would only MATCH port if keeping the rpms under 7500. When you open up the ports beyond that, you start to lose low-mid rpm performance. If, however, you will be pushing over 7500 rpms, then increasing the size of the ports will again help at those high rpms.
Pistons
I would recommend slightly less compression than 9.0:1 if you want to achieve 600 RWHP on pump gas. Otherwise, pre-detonation may become an issue before you get to that level (unless your using meth injection or testing on a DynoJet). Try to use something in the range of 8.5:1 to 8.8:1.
On my new build, I have specifically requested Wisecos, even though the motor will cost me the same $$$ regardless of whether I use Wisco or Arias. Moreover, Sam is concerned that the Wiseco's will not arrive fast enough since they are custom made for that motor, so I asked him to offer Wiseco an expedite fee to try to get them there on time. I would rather pay a little more and know that I have the Wisecos. In your case, the Wisecos are less expensive than Arias but, in my humble opinion (based upon a lot of research I might add), I prefer them to Arias and some other pistons. CP's also are supposed to be very good, but JetPilot is the only one I know running them. You might look into those as well.
Other Stuff
Everything else looks OK, but you also will need alot of other parts.
For example, you will need a wastegate relocation kit to keep the Greddy's boost from creeping at the boost levels you will need to get to 600 RWHP. Boost creep in the Greddy's can cause some serious issues at those boost levels.
You will need a clutch strong enough to hold the power if you have a manual, or upgrade your transmission with new clutch packs, etc., if you have an automatic. If you have a manual, go with a multi-disk clutch. I started with a twin disk Clutchasters FX600, but it didn't hold up for me. Now I have a Carbonetics triple disk. It is much, much stronger and much, much smoother for street driving than the clutchmasters. Each plate on the Carbonetics has probably double the surface area of the Clutchmasters. Exedy and GTM also are supposed to have good clutches, but I have never driven a car that has them, so I can't provide a comparison to the clutches I have used.
You also will need an EMS (HKS F-CON and Haltech are popular choices), a dual exhaust system 2.75" dia. or bigger, downpipes, a fuel return system, larger fuel injectors, a plenum spacer if using your stock plenum, a larger radiator, etc. An oil cooler or two also would be good, as well as a suitably sized oil catch can.
Please DO NOT use the Cometic headgasket. There have been problems with these on VQ motors. I can't opine about the Cosworth head gaskets because I don't know anybody who has ran them.
Do yourself a favor and seriously look into using the HR head gaskets or the HKS head gaskets. After speaking in depth about this issue both with Jim Wolf and Sam at GTM, as well as some other forum members, I'm using HR gaskets on my motor. I'll be pushing 700 RWHP on pump gas, and well over that with meth injection on line. FYI, the HR head gaskets cost about $60 - $70, whereas the HKS headgaskets cost $360. Nonetheless, you can't go wrong with HKS headgaskets. I have never heard of one failing on a build without aftermarket sleeves. The problems when aftermarket sleeves were used were due to the sleeves moving, not the gaskets.
Cams
What will your maximum RPM be? That will determine which cam is best for you. MAKE SURE YOU GET REV UP VERSIONS OF THESE CAMS IF YOU ARE USING A REV UP HEAD!!! The VQ35DE cams may not work.
If it will be less that 7500 rpm, (Scratch the C2's, SmallTuner reminded me, in a very polite way I might add, that you are using RevUp Heads). Look at the JWT S7R's and C8R's. You must use the JWT springs with these. They are harmonically balanced for the JWT cam profiles. I'll post their specifications in the previous page. Edit: After posting their respective specifications, I see that they both have minimum overlap. Hence, I would go with the C8Rs.
If you will be reving over 7500 RPM, BC or GTM cams. However, on the Brian Crower site, I did not see any RevUp cams listed. GTM has Stage 1, Stage 2 and Stage 3 cams for the Rev Up motor. So far, the specifications look the same as the non-RevUp motors. For high RPM use, I believe the GTM cams are the ticket.
Valves
The power level is not a problem for the stock valves, but you might want to check to see what RPM they are good to. If the conclusion is that they aren't good for the RPM you will be pushing and you need aftermarket valves, you cannot go wrong with Ferrea valves. I'm sure there are other good valves out there too, but stay away from BC valves. I have heard of them breaking when pushed hard.
Port and Polishing
As far as port and polishing, I would only MATCH port if keeping the rpms under 7500. When you open up the ports beyond that, you start to lose low-mid rpm performance. If, however, you will be pushing over 7500 rpms, then increasing the size of the ports will again help at those high rpms.
Pistons
I would recommend slightly less compression than 9.0:1 if you want to achieve 600 RWHP on pump gas. Otherwise, pre-detonation may become an issue before you get to that level (unless your using meth injection or testing on a DynoJet
). Try to use something in the range of 8.5:1 to 8.8:1.On my new build, I have specifically requested Wisecos, even though the motor will cost me the same $$$ regardless of whether I use Wisco or Arias. Moreover, Sam is concerned that the Wiseco's will not arrive fast enough since they are custom made for that motor, so I asked him to offer Wiseco an expedite fee to try to get them there on time. I would rather pay a little more and know that I have the Wisecos. In your case, the Wisecos are less expensive than Arias but, in my humble opinion (based upon a lot of research I might add), I prefer them to Arias and some other pistons. CP's also are supposed to be very good, but JetPilot is the only one I know running them. You might look into those as well.
Other Stuff
Everything else looks OK, but you also will need alot of other parts.
For example, you will need a wastegate relocation kit to keep the Greddy's boost from creeping at the boost levels you will need to get to 600 RWHP. Boost creep in the Greddy's can cause some serious issues at those boost levels.
You will need a clutch strong enough to hold the power if you have a manual, or upgrade your transmission with new clutch packs, etc., if you have an automatic. If you have a manual, go with a multi-disk clutch. I started with a twin disk Clutchasters FX600, but it didn't hold up for me. Now I have a Carbonetics triple disk. It is much, much stronger and much, much smoother for street driving than the clutchmasters. Each plate on the Carbonetics has probably double the surface area of the Clutchmasters. Exedy and GTM also are supposed to have good clutches, but I have never driven a car that has them, so I can't provide a comparison to the clutches I have used.
You also will need an EMS (HKS F-CON and Haltech are popular choices), a dual exhaust system 2.75" dia. or bigger, downpipes, a fuel return system, larger fuel injectors, a plenum spacer if using your stock plenum, a larger radiator, etc. An oil cooler or two also would be good, as well as a suitably sized oil catch can.
05-04-2009, 07:46 AM
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OP
I am also looking for 650-700whp.
I am currently going to use Cometic Head Gasket, I've also heard great things about it.
As far as cams, I am going BC3's.
My pistons 9:8:1 with eagle rods.
Either way your motor will be in good shape with your setup.
GL.
I am also looking for 650-700whp.
I am currently going to use Cometic Head Gasket, I've also heard great things about it.
As far as cams, I am going BC3's.
My pistons 9:8:1 with eagle rods.
Either way your motor will be in good shape with your setup.
GL.
05-04-2009, 07:47 AM
#66
Hmmm...I guess there's many different views with cometic headgaskets....maxima owners who build 3.5 motors that swap into 95-01 maximas don't have any problems. Many are boosted that I can recall.
As for cosworth, I have the 96mm bore on my stock 95.5mm bore on my 2002 vq35fwd build that I swapped in my 99 maxima. I'm boosting this motor as well...just been lazy..I do have all the parts though =] STOCK heads and I'm hitting 7639 @ 120mph 3rd gear pull.
I was looking into a HR head gasket for my 2nd vq35 build with some head work on my maxima since nobody is running them yet. I will def consider them for the Z motor build.
As for cams, the RPM level I want to be pushing over 7500 but no more than 8000. I'm using a rev up short block but non rev up heads.
The valves, I was looking into ferrea or even supertech.
Port and polish: thanks for that info.
Pistons: I was aware about those 9:1 cr pistons that it might be too high. My 2nd choice was picking up Wiseco pistons. Is it necessary to get a .02 ob pistons or stock bore is good enough? I actually purchase the set of used pistons from JetPilot.
As for the other parts, I do have a JWT clutch/flywheel combo. I'm not sure if that clutch would hold that power level but I'll be slapping on the greddy tt kit on my stock motor. I will def look into a better clutch when the motor is built.
I also have a fast intentions 3" TD exhaust.
Where can I buy the wastegate relocation kit???
So running a UTEC is not enough? hmmm...I'll look into the others...
Thanks again for the info!
As for cosworth, I have the 96mm bore on my stock 95.5mm bore on my 2002 vq35fwd build that I swapped in my 99 maxima. I'm boosting this motor as well...just been lazy..I do have all the parts though =] STOCK heads and I'm hitting 7639 @ 120mph 3rd gear pull.
I was looking into a HR head gasket for my 2nd vq35 build with some head work on my maxima since nobody is running them yet. I will def consider them for the Z motor build.
As for cams, the RPM level I want to be pushing over 7500 but no more than 8000. I'm using a rev up short block but non rev up heads.
The valves, I was looking into ferrea or even supertech.
Port and polish: thanks for that info.
Pistons: I was aware about those 9:1 cr pistons that it might be too high. My 2nd choice was picking up Wiseco pistons. Is it necessary to get a .02 ob pistons or stock bore is good enough? I actually purchase the set of used pistons from JetPilot.
As for the other parts, I do have a JWT clutch/flywheel combo. I'm not sure if that clutch would hold that power level but I'll be slapping on the greddy tt kit on my stock motor. I will def look into a better clutch when the motor is built.
I also have a fast intentions 3" TD exhaust.
Where can I buy the wastegate relocation kit???
So running a UTEC is not enough? hmmm...I'll look into the others...
Thanks again for the info!
EDIT: I just called JWT. Per Ben, the maximum RPM for the C2 cams is 7600 - 7700 rpm. Again, you must use the JWT valve springs. If you want 8000 rpm, go with BC or GTM cams.
If the block is new, stock bore is fine. If it is a used block, you are better off going 0.020" overboar and hoaning the cylinders. I don't know for sure, but would think JetPilots Arias pistons are 0.020" overboar.
JetPilot is a good guy!
Nonetheless, whenever buying used pistons, check the diameters before boaring/hoaning the cylinders. When I ran Sebring with my first motor, I had fuel pickup issues and leaned the motor out. This caused the motor to get very hot, causing the cylinder to piston wall clearences to increase a little bit.
Accoring to my machinist, who is also JetPilot's machinist, the piston to cylinder wall clearences should be about 0.0035", but I have heard of others running a 0.0030" piston to cylinder wall clearence. Cosworth specifies 0.0033" to 0.0049" clearence, but I would stick to the low side of that for a VQ motor. EDIT: According to JetPilot, Arias pistons need more piston to cylinder wall clearence than some other pistons. If you have Arias pistons, check with Arias for the cylinder wall clearences that they recommend.
I had a couple of cylinder to wall cleareances that were around 0.0050", or maybe slightly over, which caused a bit of piston slapping. So my machinist recommended getting larger boar pistons and boaring/hoaning my cylinders to match my pistions, or applying a coating the my existing pistons. He said the coating probably would not last as long as if I went with new pistons.
Another option was to get an unboared block and boar/hoan each cylinder to a specific piston. Since you already have the pistons, if you have not yet board/hoaned your block, be sure to tell your machinist to do this. As long as the pistons are in good shape, you should not have a problem.
Also, I forgot to mention the clutch. I don't think the JWT clutch is designed for 600 RWHP. Again, you better check with Jim Wolf about this before jumping. Their contact telephone number is on their web site.
EDIT: Per Ben at JWT, the JWT clutch will support 600 HP if it is properly broken in.
I have a SGP wastegate relocation kit, but given all of their recent problems, I would look elsewhere. There are other companies that make them, but you'll have to search the forum to find out who they are. I don't remember.
Last edited by ttg35fort; 06-22-2009 at 11:26 PM.
05-04-2009, 07:55 AM
#67
Unless you have a seriously oversized stroker motor, the only way I can see you getting to 650 - 700 RWHP with those pistons is to run meth injection or race gas.... Your best hope is to test on a DynoJet (which typically reads 10% higher than some of the other dynos), but still, your going to have a hard time getting there without alot of knocking.
With regard to the Cometic head gaskets, check with some of the EXPERIENCED VQ builders about this. Both Roger at Japtrix and Sam at GTM have had problems with Cometic Head Gaskets, and neither of these respected companies will even use them anymore. Indeed, both Jim Wolf (the owner of JWT) and Sam at GTM recommend the HR head gasket for my new 4.0L stroker motor (with the compression ratio in the 8's I might add), which should get to around 675 RWHP on 93 octane pump gas and 750 RWHP with meth injection.
Why not just use HR head gaskets. They are better than Cometic and they cost less.
Last edited by ttg35fort; 05-04-2009 at 08:17 AM.
05-04-2009, 10:49 AM
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If you are going to spin up to 8,000 rpm, you better call Jim Wolf before buying JWT cams. That might be pushing it for them. Jim will be able to give you a definite answer on this.
EDIT: I just called JWT. Per Ben, the maximum RPM for the C2 cams is 7600 - 7700 rpm. Again, you must use the JWT valve springs. If you want 8000 rpm, go with BC or GTM cams.
If the block is new, stock bore is fine. If it is a used block, you are better off going 0.020" overboar and hoaning the cylinders. I don't know for sure, but would think JetPilots Arias pistons are 0.020" overboar.
JetPilot is a good guy!
Nonetheless, whenever buying used pistons, check the diameters before boaring/hoaning the cylinders. When I ran Sebring with my first motor, I had fuel pickup issues and leaned the motor out. This caused the motor to get very hot, causing the pistons to shrink a little bit.
Accoring to my machinist, who is also JetPilot's machinist, the piston to cylinder wall clearences should be about 0.0035", but I have heard of others running a 0.0030" piston to cylinder wall clearence. Cosworth specifies 0.0033" to 0.0049" clearence, but I would stick to the low side of that for a VQ motor.
I had a couple of cylinder to wall cleareances that were around 0.0050", or maybe slightly over, which caused a bit of piston slapping. So my machinist recommended getting new pistons or applying a coating the my existing pistons. He said the coating probably would not last as long as if I went with new pistons.
Another option was to get an unboared block and boar/hoan each cylinder to a specific piston. Since you already have the pistons, if you have not yet board/hoaned your block, be sure to tell your machinist to do this. As long as the pistons are in good shape, you should not have a problem.
Also, I forgot to mention the clutch. I don't think the JWT clutch is designed for 600 RWHP. Again, you better check with Jim Wolf about this before jumping. Their contact telephone number is on their web site.
EDIT: Per Ben at JWT, the JWT clutch will support 600 HP if it is properly broken in.
I have a SGP wastegate relocation kit, but given all of their recent problems, I would look elsewhere. There are other companies that make them, but you'll have to search the forum to find out who they are. I don't remember.
EDIT: I just called JWT. Per Ben, the maximum RPM for the C2 cams is 7600 - 7700 rpm. Again, you must use the JWT valve springs. If you want 8000 rpm, go with BC or GTM cams.
If the block is new, stock bore is fine. If it is a used block, you are better off going 0.020" overboar and hoaning the cylinders. I don't know for sure, but would think JetPilots Arias pistons are 0.020" overboar.
JetPilot is a good guy!
Nonetheless, whenever buying used pistons, check the diameters before boaring/hoaning the cylinders. When I ran Sebring with my first motor, I had fuel pickup issues and leaned the motor out. This caused the motor to get very hot, causing the pistons to shrink a little bit.
Accoring to my machinist, who is also JetPilot's machinist, the piston to cylinder wall clearences should be about 0.0035", but I have heard of others running a 0.0030" piston to cylinder wall clearence. Cosworth specifies 0.0033" to 0.0049" clearence, but I would stick to the low side of that for a VQ motor.
I had a couple of cylinder to wall cleareances that were around 0.0050", or maybe slightly over, which caused a bit of piston slapping. So my machinist recommended getting new pistons or applying a coating the my existing pistons. He said the coating probably would not last as long as if I went with new pistons.
Another option was to get an unboared block and boar/hoan each cylinder to a specific piston. Since you already have the pistons, if you have not yet board/hoaned your block, be sure to tell your machinist to do this. As long as the pistons are in good shape, you should not have a problem.
Also, I forgot to mention the clutch. I don't think the JWT clutch is designed for 600 RWHP. Again, you better check with Jim Wolf about this before jumping. Their contact telephone number is on their web site.
EDIT: Per Ben at JWT, the JWT clutch will support 600 HP if it is properly broken in.
I have a SGP wastegate relocation kit, but given all of their recent problems, I would look elsewhere. There are other companies that make them, but you'll have to search the forum to find out who they are. I don't remember.
I got your PMs thanks.
As for the block, I picked up a 2006 G35 rev up motor with 12k miles. The cylinder walls look pretty clean.
Yes those Arias pistons I bought from JetPilot are 9:1 .02 ob. You did mention that using these for ~600rwhp level might not be a good idea due to pre-ignition. So i was figuring to use weisco pistons 8.8:1 stock bore and just hone the cylinder walls myself with a 320 grit flex hone or 240 grit flex hone. (from what I heard 320 grit doesnt take out much material off the cylinder) but just to clean up the walls and make a nice crosshatch.
I will def look into that info on the cylinder wall clearances. How much does your machinist charge to do the .02" ob?
By the way, how thick are those HR head gaskets? They are a lot cheaper than non rev up head gaskets for sure!
05-04-2009, 10:56 AM
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your going to swap out a set of 9:1 pistons for a set of 8.8:1 pistons based on worries about pre-ignition? getting it properly tuned should be your biggest worry as far as pre-ignition is concerned. There won't be any measure of safety in .2 points on static CR
piston to wall clearance will vary by piston manufacturer - they each use different alloys, so they expand and contract at different rates. Oil type, engine rpm range, sustained rpm, etc all factor in. Let the machinist tell you what to use, not the other way around - he builds it, and ultimately it's his *** on the line (assuming a good tune)
piston to wall clearance will vary by piston manufacturer - they each use different alloys, so they expand and contract at different rates. Oil type, engine rpm range, sustained rpm, etc all factor in. Let the machinist tell you what to use, not the other way around - he builds it, and ultimately it's his *** on the line (assuming a good tune)
05-04-2009, 11:07 AM
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your going to swap out a set of 9:1 pistons for a set of 8.8:1 pistons based on worries about pre-ignition? getting it properly tuned should be your biggest worry as far as pre-ignition is concerned. There won't be any measure of safety in .2 points on static CR
piston to wall clearance will vary by piston manufacturer - they each use different alloys, so they expand and contract at different rates. Oil type, engine rpm range, sustained rpm, etc all factor in. Let the machinist tell you what to use, not the other way around - he builds it, and ultimately it's his *** on the line (assuming a good tune)
piston to wall clearance will vary by piston manufacturer - they each use different alloys, so they expand and contract at different rates. Oil type, engine rpm range, sustained rpm, etc all factor in. Let the machinist tell you what to use, not the other way around - he builds it, and ultimately it's his *** on the line (assuming a good tune)
I've been looking for machinist and haven't found one to go with yet. I figured using weisco 8.8:1 pistons stock bore so I don't need to over bore the block. I can assemble everything myself thats the thing....
Do you do machine work at your shop or recommend any other shop for reasonable prices?
I'm in no rush building this motor since...I did get layed off from work =/ (damn finance industry lol) Just happen to have parts that I bought when I had money to burn =/
05-04-2009, 11:23 AM
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If you have a used block (and even if you have a brand spanking new one, as they aren't always perfect either), you would be well served to spend the extra ~$400 and have it machined. Otherwise you're just guessing, and that's a big no no when it comes to having an engine last. Do you want to chance a $25k setup to a guess? I know I wouldn't. A good machinist, like a good tuner, are the absolute most important 2 things in an engine build. The rest of it (like what cam, what engine mgmt, what injectors, etc etc) is cream cheese - people seem to spend more time selecting the parts though, I guess because it's easier to get their hands around ? Those people end up usually doing things multiple times, till they realize that assembling an engine and building an engine aren't the same thing.
I strictly stick to selling parts. There are tons of great engine builders in the tri state area. Reasonably priced is a very subjective term IMHO - I'd tried to find someone who knows what they are doing (doesn't take any sort of VQ expert mind you), and who will help you understand the magnitude of your undertaking - those are the guys worth spending $ with, whatever their asking price may be.
I strictly stick to selling parts. There are tons of great engine builders in the tri state area. Reasonably priced is a very subjective term IMHO - I'd tried to find someone who knows what they are doing (doesn't take any sort of VQ expert mind you), and who will help you understand the magnitude of your undertaking - those are the guys worth spending $ with, whatever their asking price may be.
05-04-2009, 11:31 AM
#72
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9.8:1 on a turbo motor?
Unless you have a seriously oversized stroker motor, the only way I can see you getting to 650 - 700 RWHP with those pistons is to run meth injection or race gas.... Your best hope is to test on a DynoJet (which typically reads 10% higher than some of the other dynos), but still, your going to have a hard time getting there without alot of knocking.
With regard to the Cometic head gaskets, check with some of the EXPERIENCED VQ builders about this. Both Roger at Japtrix and Sam at GTM have had problems with Cometic Head Gaskets, and neither of these respected companies will even use them anymore. Indeed, both Jim Wolf (the owner of JWT) and Sam at GTM recommend the HR head gasket for my new 4.0L stroker motor (with the compression ratio in the 8's I might add), which should get to around 675 RWHP on 93 octane pump gas and 750 RWHP with meth injection.
Why not just use HR head gaskets. They are better than Cometic and they cost less.
Unless you have a seriously oversized stroker motor, the only way I can see you getting to 650 - 700 RWHP with those pistons is to run meth injection or race gas.... Your best hope is to test on a DynoJet (which typically reads 10% higher than some of the other dynos), but still, your going to have a hard time getting there without alot of knocking.
With regard to the Cometic head gaskets, check with some of the EXPERIENCED VQ builders about this. Both Roger at Japtrix and Sam at GTM have had problems with Cometic Head Gaskets, and neither of these respected companies will even use them anymore. Indeed, both Jim Wolf (the owner of JWT) and Sam at GTM recommend the HR head gasket for my new 4.0L stroker motor (with the compression ratio in the 8's I might add), which should get to around 675 RWHP on 93 octane pump gas and 750 RWHP with meth injection.
Why not just use HR head gaskets. They are better than Cometic and they cost less.
compression has next to nothing to do with peak power...
i will look into the HR head gasket.
05-04-2009, 11:37 AM
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it's a factor, yes, like other things are
if your engine is tuned to such a ragged edge that .2 points of static compression ratio is the difference between it surviving vs blowing itself into little pieces, then you're likely not building a motor based on forum recommendations
if your engine is tuned to such a ragged edge that .2 points of static compression ratio is the difference between it surviving vs blowing itself into little pieces, then you're likely not building a motor based on forum recommendations
05-04-2009, 11:39 AM
#75
I spin to 8000rpm's with JWt valvetrain and BC3 cams
Ray @ PFS goes to slightly more than that on stock valvetrain, sounds crazy no bent valves, no issues thus far.
My rev limit IIRC is 8500rpm's but I havent hit nor do I plan to, this is track/race only and since I havent driven my POS since November...blah
Ray @ PFS goes to slightly more than that on stock valvetrain, sounds crazy no bent valves, no issues thus far.
My rev limit IIRC is 8500rpm's but I havent hit nor do I plan to, this is track/race only and since I havent driven my POS since November...blah
05-04-2009, 11:43 AM
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8400 on stock valves here (since 2007) and just NISMO springs - no forced induction on my end, but nevertheless, the rpms are there A lightweight valve would certainly improve efficiency, and spin a bit quicker, I just didn't see the need for my intended purposes, nor did my builder.
A lightweight valve would certainly improve efficiency, and spin a bit quicker, I just didn't see the need for my intended purposes, nor did my builder.
05-04-2009, 11:54 AM
#79
it's a factor, yes, like other things are
if your engine is tuned to such a ragged edge that .2 points of static compression ratio is the difference between it surviving vs blowing itself into little pieces, then you're likely not building a motor based on forum recommendations
if your engine is tuned to such a ragged edge that .2 points of static compression ratio is the difference between it surviving vs blowing itself into little pieces, then you're likely not building a motor based on forum recommendations
In my last build, I had 8.8:1 and we pulled the timing back to around 10-11 degrees at the boost levels we needed to get to 600 RWHP. Now, this was a safe, conservative tune. However, with the boost he will need to get to his horsepower levels, he will be knocking unless he does one of the three things I mentioned, that is: run meth injection, run race gas, or use an oversized stroker motor. 650 - 700 RWHP is not going to happen on pump gas in a 3.5L VQ35DE motor with 9.8:1 compression without a lot of knocking. If he doesn't mind the consequences of knocking, then that's his choice. But he certainly should not be encouraged to do so (unless your looking to sell more parts when his motor prematurely gives out).
05-04-2009, 12:02 PM
#80
Compression will significantly affect your engine's predisposition to knock and therefore it will affect your ability to make power, safely. Lowering compression increases the margin for safety before knock, particularly on pump gas. You can make power with high compression and C16, no problem of course, so in that respect perhaps you are correct.
One other thing to consider. If you look at a datalog with a 5 msec sampling rate and watch how boost that looks flat at x psi on a dynograph actually oscillates significantly above and below that median value, you'll realize how you can incite knock at what might be considered a "safe" boost level. Most boost controller sample at 30 Hz and changes are relatively slow to respond compared to engine speed. So at 16 psi, cylinders may be seeing 18-20 psi at regular intervals...
Compression ratio is a multiplication factor that amplifies peak cylinder pressure and so small changes do have a large impact. Having a lower ratio provides more granularity among the other factors that are under your control (boost, timing), so that you can more closely approach optimal power levels for your setup without the risk of knock.
Last edited by rcdash; 05-04-2009 at 12:06 PM.