3.7L Done Inexpensively.
11-11-2005, 10:10 AM
#22
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Originally Posted by Nathan
I got .820" on the VQ rod width
11-12-2005, 07:07 AM
#23
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Originally Posted by tilleys99
same here. BTW other options are VK45 rods or vh45 rods i have a full set of either. They both have same size rod main and same size pin but lengths are just a lil longer.
11-12-2005, 07:19 AM
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Originally Posted by tilleys99
same here. BTW other options are VK45 rods or vh45 rods i have a full set of either. They both have same size rod main and same size pin but lengths are just a lil longer.
11-13-2005, 06:22 AM
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Originally Posted by audiblemayhem
i have been doing some more research on this matter. i have a block apart and the crank sitting here, i would love to be able to fit 350SB parts in here....
then i could run a 250 shot with no worries....
then i could run a 250 shot with no worries....
If all you wanted to do was run with SB rods and not stroke the motor, you'd be better off just running Eagle rods for the VQ. To run SB rods you'll have to grind the rod journals down to 2.100" and machine about .060" off each side of the rods to fit the journals. By the time you get all of that done you'd have exceeded to cost for a set of Eagle VQ rods.
It would be feasible to do this if you were looking for a special feature in the rods such as ultra light weight, aluminum or titanium, that otherwise wouldn't be available for the VQ.
11-13-2005, 02:38 PM
#28
oh yeah i know what you mean, i would like to able to stroke the motor plus have such a diverse selection of parts avail. this would open all a whole new window of opportunity for the vq, i am just starting to build and work with them so i am learning all i can, i was kidding about the nitrous comment, sorry you took it the wrong way
08-13-2010, 09:42 PM
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I'm sure I'll catch a lot of flack for this but this method of stroking has been around for decades and was real popular amongst hotrodders..
You don't neccessarily HAVE to find a shop that deals strictly with imports or the VQ specifically, only one that has a lot of experience in working with crankshafts. For that, it would be beneficial that you try and find a shop that does cater to the hotrodder bunch as most of these guys really turn out good precision work for not that much $$$$.
What's odd about this set-up is that you'd use SBC (small block chevy) rods which are very close in measurement to the stock VQ35 rods as you'll see a little further down. Another benefit to using SBC rods is that there are just so many of them out there. Billet, forged, cast, aluminum, steel, light weight, ultra light weight, etc., etc., etc. AND they can be had for fairly cheap!! Also custom pistons will have to be machined which according to a quote from Arias should be about $145 per piston ($20 additional if buttons are used). Of course you'll have to choose your comp. ratio (11.5:1 for NA or 8.5:1 - 9.0:1 for FI).
I kinda took the liberty of finding all the neccessary specs and playing with the numbers thus coming up with conservative measurements that shouldn't require too much block clearancing or machining(hopefully)
.
Stock VQ specs we need to be concerned with for stroking:
Deck Height = 8.464" (215mm)
Stroke = 3.205" (81.4mm)
Crank Throw (stroke/2) = 1.6025" (40.7mm)
Rod Length = 5.677" (144.2mm)
Rod Big End Diameter w/bearings = 2.165" (55mm)
Compression Height = 1.168" (29.67mm)
Deck Clearance = .025" (.635mm)
First thing is to have the crankshaft rod journals offset ground by 2.5mm. This will increase the stroke by 5mm total bringing the final number to 3.40" (86.4mm).
Now that you have offset ground the rod journals by 2.5mm you have essentially reduced the diameter of those journals the same (2.5mm). The new diameters will be 2.067" (52.5mm).
The SBC rods you'd use are the standard size 350 with a length of 5.7" and a big end diameter (w/bearings) of 2.100". You can see that the rod journal diameter is smaller than SBC rods big end diameter by .033". To bring the rods closer to journal diameter you'll need .040" undersized bearings. Federal Mogul, Clevite, etc. all make any kind of rod bearings you can think of for any application you can dream up.
With the new undersized bearings you're basically reducing the diameter of the rod big end by .040" to a final diameter of 2.06" (52.32mm). Now the journal diameter is actually larger than the rod big end by .007" and can be finished / polished down to size.. All done with crank grinding and really shouldn't be more than $500.
As far as pistons go the compression height has to be lowered to prevent the piston from coming too far out of the bore. Very simple task!!! You've increased crank throw by .098" (2.5mm) from crankshaft grinding and you've also increased rod length by .023" (.58mm) from using longer SBC rods. Essentially this just means that if you put stock pistons back in with stock comp. height they'll extend beyond the blocks deck by .121" (3.07mm). Thus, on the new pistons, the comp height has to be reduced by the same amount to prevent that, bringing the new height to 1.047" (26.59mm). Also the piston pin bores need to be machined to fit the SBC rods small end.
That's all there really is to it in general. I know it may seem like a lot but again it's a very simple and inexpensive alternative to stroker kits. For a bulletproof NA motor with high comp pistons I'd be figure anywhere between $1800 and $1900 for everything if you build the engine back-up yourself. Little bit more if you have a builder do it for you.
You don't neccessarily HAVE to find a shop that deals strictly with imports or the VQ specifically, only one that has a lot of experience in working with crankshafts. For that, it would be beneficial that you try and find a shop that does cater to the hotrodder bunch as most of these guys really turn out good precision work for not that much $$$$.
What's odd about this set-up is that you'd use SBC (small block chevy) rods which are very close in measurement to the stock VQ35 rods as you'll see a little further down. Another benefit to using SBC rods is that there are just so many of them out there. Billet, forged, cast, aluminum, steel, light weight, ultra light weight, etc., etc., etc. AND they can be had for fairly cheap!! Also custom pistons will have to be machined which according to a quote from Arias should be about $145 per piston ($20 additional if buttons are used). Of course you'll have to choose your comp. ratio (11.5:1 for NA or 8.5:1 - 9.0:1 for FI).
I kinda took the liberty of finding all the neccessary specs and playing with the numbers thus coming up with conservative measurements that shouldn't require too much block clearancing or machining(hopefully)
. Stock VQ specs we need to be concerned with for stroking:
Deck Height = 8.464" (215mm)
Stroke = 3.205" (81.4mm)
Crank Throw (stroke/2) = 1.6025" (40.7mm)
Rod Length = 5.677" (144.2mm)
Rod Big End Diameter w/bearings = 2.165" (55mm)
Compression Height = 1.168" (29.67mm)
Deck Clearance = .025" (.635mm)
First thing is to have the crankshaft rod journals offset ground by 2.5mm. This will increase the stroke by 5mm total bringing the final number to 3.40" (86.4mm).
Now that you have offset ground the rod journals by 2.5mm you have essentially reduced the diameter of those journals the same (2.5mm). The new diameters will be 2.067" (52.5mm).
The SBC rods you'd use are the standard size 350 with a length of 5.7" and a big end diameter (w/bearings) of 2.100". You can see that the rod journal diameter is smaller than SBC rods big end diameter by .033". To bring the rods closer to journal diameter you'll need .040" undersized bearings. Federal Mogul, Clevite, etc. all make any kind of rod bearings you can think of for any application you can dream up.
With the new undersized bearings you're basically reducing the diameter of the rod big end by .040" to a final diameter of 2.06" (52.32mm). Now the journal diameter is actually larger than the rod big end by .007" and can be finished / polished down to size.. All done with crank grinding and really shouldn't be more than $500.
As far as pistons go the compression height has to be lowered to prevent the piston from coming too far out of the bore. Very simple task!!! You've increased crank throw by .098" (2.5mm) from crankshaft grinding and you've also increased rod length by .023" (.58mm) from using longer SBC rods. Essentially this just means that if you put stock pistons back in with stock comp. height they'll extend beyond the blocks deck by .121" (3.07mm). Thus, on the new pistons, the comp height has to be reduced by the same amount to prevent that, bringing the new height to 1.047" (26.59mm). Also the piston pin bores need to be machined to fit the SBC rods small end.
That's all there really is to it in general. I know it may seem like a lot but again it's a very simple and inexpensive alternative to stroker kits. For a bulletproof NA motor with high comp pistons I'd be figure anywhere between $1800 and $1900 for everything if you build the engine back-up yourself. Little bit more if you have a builder do it for you.
You say that by offset grinding the journal 2.5mm, that you're increasing the throw by .098", but, in fact, it's less than that. When you offset grind.. In order to figure out the change in rod throw, you have to take the old diameter (2.145"), and subract the new diameter (2.000" for SBC small journal rods). Divide the difference, and you get the change in the crank throw. .
So, the difference between a stock journal (2.145"), and a SBC rod journal (2.000") is .145". Half of that would be .0725", which would be the increase in the rod throw. The increase in stroke would be .145", for a new stroke of 3.350".
Using a 96mm bore, and a 85.1mm (3.350") stroke, you get 3696cc, or, right at 3.7 liters. With a standard bore, you get 3658cc, which rounds up to a 3.7 liter as well, but, is 50cc short of a true 3.7 liter.
Using a 5.7" rod, we have a new rod/stroke ratio of 1.7:1, which is still pretty darn good, and could be safely revved out to 8K rpm. Piston speed at 8K rpm is 22.7 meters per second, which is well under the 25 meters per second "rule of thumb".
So, in summing this up.. I think that it's well worth the money to get this done. I am going to offer setups in the near future, after some in house testing.
Travis
08-14-2010, 07:52 AM
#30
This was a nice blast from the past - a good read. Good bump Travis - and good luck. I've always wondered what the limiting factor in my setup was in terms of rpm limit. With a stock rod/stroke ratio (eagle H beam rods, and Arias ED pistons 9:1 ratio) with my built motor and jwt cams/springs, I've still never felt comfortable pushing past 7k rpms. I didn't build with 8k rpms in mind - would you mind commenting what recommendations you would make for your customers wanting to spin reliably to 8k? In retrospect, I wish I had put on a billet girdle to help maintain bearing clearances at those high speeds...
Last edited by rcdash; 08-14-2010 at 07:54 AM.
08-14-2010, 12:53 PM
#33
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This was a nice blast from the past - a good read. Good bump Travis - and good luck. I've always wondered what the limiting factor in my setup was in terms of rpm limit. With a stock rod/stroke ratio (eagle H beam rods, and Arias ED pistons 9:1 ratio) with my built motor and jwt cams/springs, I've still never felt comfortable pushing past 7k rpms. I didn't build with 8k rpms in mind - would you mind commenting what recommendations you would make for your customers wanting to spin reliably to 8k? In retrospect, I wish I had put on a billet girdle to help maintain bearing clearances at those high speeds...
I've built several VQ's for Spec V's (Sentra) with nothing more than pistons/rods, C8 or C9 cams with JWT's springs, revup oil pump, and a good balance on the rotating assembly. C8's/C9's will make power all the way out to 8K.
Here's a video messing around with my buddy's Spec V that we built..
http://www.youtube.com/watch?v=dsIz4eEe_lU
Spins to 8K, and runs 12.20's @ 110-111mph, all motor.
You're 9:1 C/R, so I assume that you're turbocharged.. In that case a set of C2's would work great, but, I would go with a slightly heavier valve spring, just because of the added pressure (boost) on the backside of the valve. But, you could go 75-7600rpm with C2's/boosted and make power out to there as well.
Travis
Last edited by Trav4011; 08-14-2010 at 12:58 PM.
08-14-2010, 01:07 PM
#35
I know that this is a really old thread.. but, I wanted to point out something, as I'm about to start building these setups for my customers..
You say that by offset grinding the journal 2.5mm, that you're increasing the throw by .098", but, in fact, it's less than that. When you offset grind.. In order to figure out the change in rod throw, you have to take the old diameter (2.145"), and subract the new diameter (2.000" for SBC small journal rods). Divide the difference, and you get the change in the crank throw. .
So, the difference between a stock journal (2.145"), and a SBC rod journal (2.000") is .145". Half of that would be .0725", which would be the increase in the rod throw. The increase in stroke would be .145", for a new stroke of 3.350".
Using a 96mm bore, and a 85.1mm (3.350") stroke, you get 3696cc, or, right at 3.7 liters. With a standard bore, you get 3658cc, which rounds up to a 3.7 liter as well, but, is 50cc short of a true 3.7 liter.
Using a 5.7" rod, we have a new rod/stroke ratio of 1.7:1, which is still pretty darn good, and could be safely revved out to 8K rpm. Piston speed at 8K rpm is 22.7 meters per second, which is well under the 25 meters per second "rule of thumb".
So, in summing this up.. I think that it's well worth the money to get this done. I am going to offer setups in the near future, after some in house testing.
Travis
You say that by offset grinding the journal 2.5mm, that you're increasing the throw by .098", but, in fact, it's less than that. When you offset grind.. In order to figure out the change in rod throw, you have to take the old diameter (2.145"), and subract the new diameter (2.000" for SBC small journal rods). Divide the difference, and you get the change in the crank throw. .
So, the difference between a stock journal (2.145"), and a SBC rod journal (2.000") is .145". Half of that would be .0725", which would be the increase in the rod throw. The increase in stroke would be .145", for a new stroke of 3.350".
Using a 96mm bore, and a 85.1mm (3.350") stroke, you get 3696cc, or, right at 3.7 liters. With a standard bore, you get 3658cc, which rounds up to a 3.7 liter as well, but, is 50cc short of a true 3.7 liter.
Using a 5.7" rod, we have a new rod/stroke ratio of 1.7:1, which is still pretty darn good, and could be safely revved out to 8K rpm. Piston speed at 8K rpm is 22.7 meters per second, which is well under the 25 meters per second "rule of thumb".
So, in summing this up.. I think that it's well worth the money to get this done. I am going to offer setups in the near future, after some in house testing.
Travis
Would these set-ups be for bolt up n/a power? I assume you mean built blocks?
08-14-2010, 01:22 PM
#36
Honestly, there's really nothing from preventing you from going to 8K, now.. The stock rod/stroke ratio is 1.77:1.. which means that at 8K rpm, your piston speed is around 21.7 meters per second. This is WELL under the accepted limit of 25 meters per second.
I've built several VQ's for Spec V's (Sentra) with nothing more than pistons/rods, C8 or C9 cams with JWT's springs, revup oil pump, and a good balance on the rotating assembly. C8's/C9's will make power all the way out to 8K.
Travis
I've built several VQ's for Spec V's (Sentra) with nothing more than pistons/rods, C8 or C9 cams with JWT's springs, revup oil pump, and a good balance on the rotating assembly. C8's/C9's will make power all the way out to 8K.
Travis
08-14-2010, 09:03 PM
#37
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OMG why the F does everyone try to reinvent the wheel??? nissan already made a stroker engine 380RS ring a bell??? to fill you in on the information... the crucial part of building crankshafts is main and rod overlap... the more overlap you have the stonger the crank... think SR20 or RB crank... little or no overlap severly weakens the crank and then exotic material have to be used and still it is a crap shoot... the machining of rod jounrals is a practice used on engines that rarely see 7k rpm... that would be pretty boring in a Z having a 7k redline...
so the 380RS??? well everyone and their parrot know that the crank main journal diameter jumped up for the HR motor... to the same size as a similar engine VR... displacment 3.8liters... yup guys and girls... 380RS is a HR with GTR35 crank... haltech engine managment... high flow cats... add ITBs with a sick carbon fiber airbox, speed density, and long tube headers and you have a 380RS-C
PLEASE for the love of god stop with the dream stroker kits to "save money" the cheap comes out expensive in the end... I will blow my head off next time I hear about a VQ40 crank into a 3.5 block... its not going to happen unless you flat cut it and then it WILL crack the crank because of very little journal overlap
so the 380RS??? well everyone and their parrot know that the crank main journal diameter jumped up for the HR motor... to the same size as a similar engine VR... displacment 3.8liters... yup guys and girls... 380RS is a HR with GTR35 crank... haltech engine managment... high flow cats... add ITBs with a sick carbon fiber airbox, speed density, and long tube headers and you have a 380RS-C
PLEASE for the love of god stop with the dream stroker kits to "save money" the cheap comes out expensive in the end... I will blow my head off next time I hear about a VQ40 crank into a 3.5 block... its not going to happen unless you flat cut it and then it WILL crack the crank because of very little journal overlap
08-14-2010, 09:15 PM
#38
Registered User
Might want to have that temper and stress level looked at professionally man....
Otherwise the next "stroker" we might see will be you.
Otherwise the next "stroker" we might see will be you.
Last edited by Tackett; 08-14-2010 at 09:17 PM.
08-14-2010, 09:29 PM
#39
PLEASE for the love of god stop with the dream stroker kits to "save money" the cheap comes out expensive in the end... I will blow my head off next time I hear about a VQ40 crank into a 3.5 block... its not going to happen unless you flat cut it and then it WILL crack the crank because of very little journal overlap
Take video, please.
