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We are building SC300 with a 2JZ-GE NA for a Bonneville Land Speed record attempt. We're working through all the engine mods including a lot of head work. Based on the regulations we will need to run VP Racing Fuel C14. Possibly C14+ but it's unclear if that will pass tech.

Does anyone have high compression piston recommendations. I'm guessing since high compression NA motors aren't very popular our options are limited and we may be stuck with full custom solution.
 

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Yeah, you'll want custom anyway to keep the weight low so it can spin higher without falling apart.
I recommend contacting JE and explaining what you're trying to do.
How high are you trying to spin the motor? What class are you racing?
 

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Discussion Starter #3
How high are you trying to spin the motor? What class are you racing?
I think we are going to target 9,000 RPM +/-.

Here's some of the records we are looking at:

F/PRO Class (Production Category)
  • Bonneville current record: 167.158 mph
F/GC Class (Unblown Gas Coupe)
  • Bonneville current record: 164.845 mph
F/GALT Class (Unblown Gas Altered Coupe)
  • Bonneville current record: 174.208 mph
F/GCC Class (Unblown Gas Competition Coupe)
  • Bonneville current record: 186.387 mph
Based on the following basic assumptions:

Cd: .31
Frontal Area: 23 sq. ft.
Weight: 2800 lbs

170 mph would require about 254hp. Since we are on the coast in California we expect to lose about 12% because of altitude which means we are going to need to make about 289hp here in CA. We're estimating we'll lose another 12% in the drivetrain so we're then look at about 328hp at the flywheel. For the higher end classes we might be able to get the Cd down to .27. At .27 Cd we should be able to run a bit over 190mph at 328hp at the flywheel.
 

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Subscribed to see where this project heads.

Good luck in acquiring the custom pistons. If it isnt too much of a hassle, would you mind uploading images of any custom parts you get made for the project, please?
 

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Subscribed as well! Very interesting project, please keep us updated on here!

Only a few people decide to go with NA power on these 2JZ-GE motors but they are out there. For example LRG Soup with his epic ITB build and also myself with my Club Sport build.

Again, please keep us updated, very interested in how this turns out!

Regards from Europe,
Herb
 

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170 mph would require about 254hp. Since we are on the coast in California we expect to lose about 12% because of altitude which means we are going to need to make about 289hp here in CA. We're estimating we'll lose another 12% in the drivetrain so we're then look at about 328hp at the flywheel. For the higher end classes we might be able to get the Cd down to .27. At .27 Cd we should be able to run a bit over 190mph at 328hp at the flywheel.
Should be pretty easy to do. I'd recommend the VVTi head to get a much broader torque curve that will carry the power to the higher RPM and cams. Look at the Honda K20 motors. The same bore and stroke, just a 4 cyl. Basic bolt-ons, upping the compression and cams and a tune and they're 250+ with ease. 14:1 is probably way too high of a compression, 12.5:1 would be a lot more ideal.
At the speeds you're going, a front facing intake manifold with an intake protruding through the bumper and a bellmouth on it will probably get you a mild increase in intake pressure at speed.
Always wanted to see what a 4.2L high compression build with ITBs would do.
 

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Discussion Starter #7
Should be pretty easy to do. I'd recommend the VVTi head to get a much broader torque curve that will carry the power to the higher RPM and cams. Look at the Honda K20 motors. The same bore and stroke, just a 4 cyl. Basic bolt-ons, upping the compression and cams and a tune and they're 250+ with ease. 14:1 is probably way too high of a compression, 12.5:1 would be a lot more ideal.
At the speeds you're going, a front facing intake manifold with an intake protruding through the bumper and a bellmouth on it will probably get you a mild increase in intake pressure at speed.
Always wanted to see what a 4.2L high compression build with ITBs would do.
Thanks for the input. Since we have so much time to get up to speed at Bonneville, 2.5 miles on the short course, we decided to ditch the VVT-i just to simplify everything. VVT-i advantage looks like it starts flattening out at about 5,000 RPM. We are somewhat grip limited on the salt as well so low-end torque just spins the skinny ass tires we run.

We picked the highest energy fuel that was legal which is the VP C14. Its operating sweet spot is above 14:1 which is why we targeted such high compression. We're going to need everything we can get to go after these records. They are surprisingly difficult to break because the aero rules are so strict and that's one of the biggest challenges out there.

Thanks again for the continued input. We don't have a lot of experience with these motors. Most all our experience is with the BMW S54 which we ran as part of our Formula Drift program a few years back.
 

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Are you using an aftermarket ECU so you can adjust fuel trim and ignition timing? I was thinking of some other easy and cheap ways you could get a little more out of that front facing intake manifold and external bellmouth intake I had mentioned earlier. If you can move the TB away from the manifold, it will give the air some distance to straighten out, and hopefully help minimize flow issues to cyl 1. Shouldn't be too hard, just have to jig up a little mount for the TB to bolt to, and attach the mount to the headlight bracket or where the battery use to be. Normally you would want the TB to be as close to the ports as possible for throttle response. You don't need throttle response, you need airflow.
Another thing, go with a 102mm Chevy TB. Basically a four inch intake system. Between the TB and manifold use a 102mm to 76mm reducer to get down to a pipe size that will bolt up to the manifold and have a smooth transition. If you have the tools and ability, port match the intake manifold to the inlet ports. You mentioned head work being done, so I'm gussing they opened up the ports a bit. Main thing is you're trying to reduce any surface turbulance so that you get more CFM to each cylinder.
 

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Discussion Starter #9
Are you using an aftermarket ECU so you can adjust fuel trim and ignition timing?
We're going to be using AEM Infinity 506. It's still early days just finishing the tear down of the donor motor and the head is off to Indy to the head guy. Now starting the dialogue between the head guy, piston manufacturer and ourselves. General thought is that 14.5:1 is a good target CR. We do though need to work through clearance and piston shape given most are recommending pretty aggressive cam since we don't care much about low end performance. It's possible (per regs) that we might be able to run VP Racing C25 which would be nice.

The EFI Hardware ITBs we are planning on running have a tapered bore so at the inlet of the TB it is 50mm then has a step down to 48mm and then finally down to 45mm. Given the theory of shorter trumpets, better top-end HP I'm guess we'll be running 50mm maybe 75mm. I guess we'll ultimately find out what works on the dyno and testing.

I few pics from the teardown.

251272
251273
251274
 

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You don't need the ITBs. No need for throttle response on a top speed run, so you can save a lot of money there.
The problem you're going to run into is gearing vs HP vs MPH.
I'd buy this dry sump setup with the saved money from passing on the ITBs
Killer deal, and will probably pay for itself in potential parts failures if you don't use it.
 
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