High-Comp Time!
04-05-2010, 06:29 PM
#1
High-Comp Time!
Hey Guys,
As I've mentioned here and there it's time to bump the compression and see what happens. JE were happy to work with us and helped us create a custom set of pistons with a few very neat features.
This is my first engine build so I wanted to keep it relatively affordable so that if it grenades I don't lose too many tears over it. For that reason I just went with a revup oil pump for some added RPM ability as well as affordable Eagle rods - which actually appear quite nice, but what do I know. The crank was dynamically balanced for the rods and pistons, and the machine work was done by a local shop that I've worked with before.
Finally had some time to put the components together and as I said before, it's my first engine build so I hope everything runs smoothly. The rod oil clearance is a little bit tighter than I'd like (or I think I'd like), but should still be acceptable. I'm using all Nissan bearings as I've run many endurance races with them without failure, so why fix something that isn't broken right?
Here are the details and some pictures of the build:
JE Pistons are designed for 12.3:1 compression, upon fitting to the heads I realized there was zero clearance to the spark plugs so some reliefs were cut. A small washer to raise the plug will still be required, or changing to a side electrode style plug. The pistons also had some weight reduction features to help with the extended high RPM use, such as manual under-dome material removal, skirt thinning and a thinner, stronger piston pin. There are also some lateral gas ports in the top compression ring land to help prevent ring flutter, which is no good for keeping all that compression in the cylinder!
Everything else is standard in the build, Clark from JWT has suggested using the HR headgaskets to help balance the water temperature across the two heads, some ARP main studs and head studs and that's about it!
I had the machine shop do me up a nice sleeve to aid with piston installation. It has a gentle taper to the block diameter that allowed me to load the piston and compress the rings and then just pop it right into the bore. V8 guys use them a lot and it just seems like a better method than clamping the piston with some universal tool. Best $80 I ever spent.
As I've mentioned here and there it's time to bump the compression and see what happens. JE were happy to work with us and helped us create a custom set of pistons with a few very neat features.
This is my first engine build so I wanted to keep it relatively affordable so that if it grenades I don't lose too many tears over it. For that reason I just went with a revup oil pump for some added RPM ability as well as affordable Eagle rods - which actually appear quite nice, but what do I know. The crank was dynamically balanced for the rods and pistons, and the machine work was done by a local shop that I've worked with before.
Finally had some time to put the components together and as I said before, it's my first engine build so I hope everything runs smoothly. The rod oil clearance is a little bit tighter than I'd like (or I think I'd like), but should still be acceptable. I'm using all Nissan bearings as I've run many endurance races with them without failure, so why fix something that isn't broken right?
Here are the details and some pictures of the build:
JE Pistons are designed for 12.3:1 compression, upon fitting to the heads I realized there was zero clearance to the spark plugs so some reliefs were cut. A small washer to raise the plug will still be required, or changing to a side electrode style plug. The pistons also had some weight reduction features to help with the extended high RPM use, such as manual under-dome material removal, skirt thinning and a thinner, stronger piston pin. There are also some lateral gas ports in the top compression ring land to help prevent ring flutter, which is no good for keeping all that compression in the cylinder!
Everything else is standard in the build, Clark from JWT has suggested using the HR headgaskets to help balance the water temperature across the two heads, some ARP main studs and head studs and that's about it!
I had the machine shop do me up a nice sleeve to aid with piston installation. It has a gentle taper to the block diameter that allowed me to load the piston and compress the rings and then just pop it right into the bore. V8 guys use them a lot and it just seems like a better method than clamping the piston with some universal tool. Best $80 I ever spent.
Last edited by SGSash; 04-05-2010 at 06:30 PM.
So what fuel will this motor be running?
04-06-2010, 07:42 AM
#6
Wiseco makes those sleeves and there $30, but its worth every penny for sure. I hope the heads are getting a race valve job or a little attention because from the factory there is some nasty gouging just above the spring seat. But damn you guys have taken intake and exhaust to a whole new level so now that you can rev it out with a bump in compression who knows.
Trending Topics
04-06-2010, 11:19 AM
#9
Registered User
Join Date: Feb 2010
Location: WA
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Now thats hi comp on the VQ. 375 at the wheels sounds good?
Audi runs 12.5.1 in the R8 V10 FSI. Pump gas should be fine if tuned right?
It's not JE's fault the pistons hit the plugs. The engine wasn't designed to run such hi comp. Thats why its custom.
Cant wait for results.
Keep up the good work
Audi runs 12.5.1 in the R8 V10 FSI. Pump gas should be fine if tuned right?
It's not JE's fault the pistons hit the plugs. The engine wasn't designed to run such hi comp. Thats why its custom.
Cant wait for results.
Keep up the good work
Last edited by niZam; 04-06-2010 at 11:21 AM.
04-06-2010, 12:48 PM
#13
[QUOTE=niZam;8276721]Now thats hi comp on the VQ. 375 at the wheels sounds good?
Audi runs 12.5.1 in the R8 V10 FSI. Pump gas should be fine if tuned right?
The Audi & for that matter all the late model high performance motors that use
11.5.1 CR & higher utilize direct injection for combustion control.
The DE @ 12.5 on pump gas will be using a timing map more similar to a FI motor & while power will be increased, detonation will be an ever present worry if the conditions vary from optimum. EG: High air temps, high water temps, pump gas not to spec.
With a high oxygen, high octane race gas the real benefit of HC will be realized
Audi runs 12.5.1 in the R8 V10 FSI. Pump gas should be fine if tuned right?
The Audi & for that matter all the late model high performance motors that use
11.5.1 CR & higher utilize direct injection for combustion control.
The DE @ 12.5 on pump gas will be using a timing map more similar to a FI motor & while power will be increased, detonation will be an ever present worry if the conditions vary from optimum. EG: High air temps, high water temps, pump gas not to spec.
With a high oxygen, high octane race gas the real benefit of HC will be realized
Last edited by Nathan; 04-06-2010 at 01:04 PM.
04-06-2010, 01:31 PM
#14
It will be very interesting to see the power increase that these pistons achieve.
In 2003 I had a talk with the boss of Nissan Motorsport South Africa.
They were the builders of the factory Paris-Daker rally raid Pathfinders.
In the conversation he said that the DE made good power up to 12.5 CR with very little to be gained above this. He also said to use the 46cc Nismo heads to increase the CR so as to keep the original combustion chamber & piston design.
Because of the intended use of the motor ( Long distance, high revving & high temp desert racing ) they settled on 11.0 CR but still made over 400 HP @ the flywheel by using Jenvey ITB's, Pectel ECU & some very high lift cams.
In 2003 I had a talk with the boss of Nissan Motorsport South Africa.
They were the builders of the factory Paris-Daker rally raid Pathfinders.
In the conversation he said that the DE made good power up to 12.5 CR with very little to be gained above this. He also said to use the 46cc Nismo heads to increase the CR so as to keep the original combustion chamber & piston design.
Because of the intended use of the motor ( Long distance, high revving & high temp desert racing ) they settled on 11.0 CR but still made over 400 HP @ the flywheel by using Jenvey ITB's, Pectel ECU & some very high lift cams.
Last edited by Nathan; 04-06-2010 at 01:38 PM.
04-07-2010, 05:49 AM
#15
In 2003 I had a talk with the boss of Nissan Motorsport South Africa.
They were the builders of the factory Paris-Daker rally raid Pathfinders.
In the conversation he said that the DE made good power up to 12.5 CR with very little to be gained above this. He also said to use the 46cc Nismo heads to increase the CR so as to keep the original combustion chamber & piston design.
They were the builders of the factory Paris-Daker rally raid Pathfinders.
In the conversation he said that the DE made good power up to 12.5 CR with very little to be gained above this. He also said to use the 46cc Nismo heads to increase the CR so as to keep the original combustion chamber & piston design.
Last edited by Zazz93; 04-07-2010 at 05:50 AM.
