Road Race Engine Build-up

[Dauntless]

I'm posting this thread here to get feedback from road racers, rather than in the general engine area. If that is a no-no, Chris, please feel free to move it.

I started converting my car for road racing a couple of years ago, but stopped to race another car and because my organization, SCCA, did not have a National class for my TSi. Starting this year, though, my Talon can run in B-Prepared and D-Prepared with its turbo, so I am looking to take up the conversion again.

The rules for the Prepared classes can be downloaded here.

To summarize for DP, the lower of the two classes with a target hp of 250 hp...

Displacement: 3000cc max...stroking and/or corporate engine swaps permitted

Head: porting permitted 1" in, stock valve size required, cams and timing free, head can be machined to raise compression to max permitted 12:1, stock intake manifold required

Block: Stock crank and rods required, pistons are free and 3-stage dry sump is permitted

Flywheel & Clutch: Stock ring gear size required in aluminum or steel; no carbon clutches, otherwise free

Turbo: Stock turbo only, but the manifold is free, intercooling free

Engine control: ECU and EFI system are free, boost adjuster must be out of reach of driver

Intake restriction: all air entering the engine must pass through a 29mm single intake restrictor (SIR) (rule says 15mm which is an error)

The SIR is how they limit the engine to 250 hp. An oddity of SIRs is that the engine needs to be able to make about 10% more power unrestricted than the SIR restricts it to. This is because the SIR introduces volumetric inefficiencies.

Therefore...the target is to build an engine following these rules that will make at least 275 hp (closer to 300 would be better), so that it will make 250 with the SIR in place.

Suggestions, questions and comments are invited!

Thanks! Stan

PS - Now you know why I put this thread here. I doubt the max hp guys are interested in a restricted engine...

 

[mavisky]

Eliminate balance shafts, 2g pistons on 6bolt rods, 7 bolt head, 90 oil filter housing with upgraded cooler. That'd be my start. Obviously run the evo 3 or similar manifold and o2 housing, and if you can switch out the 6cm 14b housing for a good 7cm housing. You'll be turning the 14b at 20+ psi, but it should be able to handle it.

Are you allowed any fuel upgrades?

 

[Dauntless]

Thanks Kyle! I think removing the balance shaft is not legal, since the rule reads "Unless a particular modification, or part, is approved in these rules, the vehicle and all of its relevant parts and assemblies shall be stock for the correct make and model of car."

Same with the 7cm housing, unless it came on the 4g63. Here is the turbo rule, "Turbocharging/Supercharging is permitted and must use the factory original unit (no aftermarket turbo/super chargers). Factory turbochargers/superchargers may not be converted to models that did not originally come equipped with forced induction. Swapping of turbo/superchargers between makes and models is prohibited."

Will the 7-bolt head fit my 6-bolt block? I bought a used good head after dropping a valve on the original. Can I tell if it is 6 or 7 bolt by looking?

I need new slugs, and alternate pistons are approved, so I will get a set of 2g's. Anyone sell them machined for the 1g, or is it required?

Thanks! Stan

 

[Dauntless]

Come to think of it, I can just swap in an entire Evo motor, since corporate engine swaps are legal. I need to do some research to see if there is a 2.3l version; if it will bolt up to my tranny (or if I need a new tranny), etc.

Thanks for planting that seed!

 

[mavisky]

Evo motors sit the wrong way, although you could try to find one of the Galant VR-4 RS motors with 510 injectors and big 16g on it. That would be a 6 bolt motor that would drop right into your car. Since ecu is open you could get the solenoid and make the Cyclone manifold operational. My buddy has a galant vr4 with a small 16g and active cyclone and it does help alot in the sub 4000rpm range, not that you'd spend alot of time there, but it still flows as well as a stock intake manifold on the top end as well.

 

[Elvenhome21]

With the balance shafts you might be able to remove the belt and leave the shaft in.

 

[underradar92]

It would be an insane amount of work to swap an EVO VIII/IX in there, but it would eliminate the NASCAR oriented (LH bias) weight deal we have going on.

 

[pneumo]

Does it say exactly where the restrictor needs to be placed? I would think it would be better to place it in the UICP than before the turbo. Either location is still 'where air enters the engine'. I'd also make sure the restrictor is built into a venturi so airflow stays smooth as it passes through it.

Or are the rules intended to limit you to 250HP?

 

[Dauntless]

The restrictor must be upstream of the compressor section, and upstream of the "recirculation valve" (BOV tube). And yes, one may use a venturi-type restrictor. Stan

 

[mavisky]

With the balance shafts you might be able to remove the belt and leave the shaft in.

But he'd have to then go in and shave down the weight from the rear shaft or the motor would shake like hell. My gf's front belt snapped and the rear was still active, thing shook like it was running on 2 1/2 cylinders.

I still say swap in the gvr4 rs motor so you get the bigger injectors and 16g then throw in the 2g pistons or even some 9.0:1 to make the motor more responsive and keep you from having to run such high boost. That'll help keep intake temps down as well and the added torque from the cyclone manifold will be awesome.

 

[Dauntless]

Okay, I've gotten some updates to the rules from my contacts at SCCA, and here are some changes and clarifications to what I listed above:

Aftermarket rods and pistons will be legal.
The porting rule is 1" in from the valve seat, so I can port the pocket, including the valve guide.
Stock intake for the engine installed is required. (what's the best intake for the 4g63/4g64?)
Did the 16g come on a 4g64? If so I can use it on a 4g64.

So, big question is...is 300-ish hp reachable with a 4g63/14g or 4g64/16g combo?

 

[mavisky]

If the motorswap is allowed then the cyclone is the "stock" intake for that motor.

No 4g64's came turbo'ed from the factory that I know of.

300hp is not impossible with the 4g63/14b setup but it will take more than the stock 7.8:1 compression pistons to do it. The best bet is one of the 4g63/16g jdm motors.

 

[pneumo]

It seems like the restrictor plate will have it's biggest affect on top end power, not low end torque. Building the motor for low end torque and maxium throttle response seems like the right way to go. Once you have those mods in place the top end power should take care of itself.

A boost controller that allows higher boost at low rpms, or a boost spike might give you some extra low end power. A MBC with a smaller bleed hole will give you a boost spike.

How about 264/264 cams or FP1?

It would be great to get a 16g on your motor, but this rule makes it seem illegal, "Swapping of turbo/superchargers between makes and models is prohibited" Or cold you get away with saying "it came with the motor"?

 

[Dauntless]

Pneumo, as long as I can prove that the engine/turbo/intake combo came on some corporate car, I should be good. After all, corporate engine swaps (as an "assembly") are permitted.

 

[steel_3d]

Are you sure stroking is permitted, as stated in your first post? Because everything else but pistons seems to be limited to the original configuration.

But if it is, I'd most definitely go with a jdm 4g63/16g combo, stroke it with the 4g64 crank, and use 8.5 or higher compression stroker pistons. Maybe aftermarket rods too, to get a full floating pin configuration for added reliability.

This will probably give you the fattest torque curve possible. It might make the high rpms completely useless though, so if you spend a lot of time around 7k, and none at all below 4k, then I'd stay with the 2.0. If you can adjust the shift points and just short shift, the stroker might work well.

I'd love to see a dyno graph of an engine with and without a restrictor. I can't quite decide in my head what it would look like. Whether it would stay flat up top, or taper off more than it would without a restrictor.

 

[Dauntless]

Thanks Steve! I have found out that they will be permitting alternate pistons and rods. However, stroking or swapping turbos to corporate engines that never came with them is not permitted. For instance, I can run a 4g63 with any turbo that came on that engine, or I can run a 4g64, but not swap a 4g63 turbo onto a 4g64 engine. Just to confirm...the 16g did come on some models of the 4g63, right?

I have never seen a dyno graph of a turbo motor with an SIR, but I know that n/a engines usually have fairly normal hp and tq curves up to the point where the restrictor starts choking the engine, and then power drops sharply from there. My guess with the 4g63 is that it would begin between 6500 and 7000 RPM.

Since I am restricted to the stock valves and the SIR, I am wondering if I shouldn't just stick with a stock lower end - maybe with 2-g pistons? Then concentrate on building additional boost through the mid-range to maximize torque with the stock turbo?

Stan

 

[pneumo]

Eagle rods and Wiseco pistons will save about 20 ounces over stock parts, which will add some responsiveness and make it quicker reving. I'd go with 9.0:1 compression since you won't get much boost out of it, plus the higher compression will make the engine more responsive. Since boost will most likely spike at midrange and drop off as the rpms go up I'd adjust the timing map to follow airflow. You'll probably need to take out timing in then midrange and add timing at high rpm. Of course datalogging will tell you where timing should be.

 

[steel_3d]

Displacement: 3000cc max...stroking and/or corporate engine swaps permitted

You might wanna correct the stroking part then. Tricked me.
The 4g64 never came with a turbo, so you're outta luck there...
Yes the 4g63 came with a 16g, in fact the evo3 is your best bet