The purpose of this is sort of weighing out risk vs. benefit from a practical physics / engineering standpoint, or from someone who has a lot of experience in tuning or scca builds. Bottom line it needs to take a lot of redlines. I want to use the car as a streetable weekend driver (built B18C) as well and will need to be a setup for pump gas, but also be able to run scca from time to time. Target power level is around 400 whp. Just figured I'd throw this out there and see what people are using and if anyone has any opinions outside of the drag racing world since the nature of endurance racing is much different on your engine.

-First off, yes, high compression will “spool the turbo quicker”, true, but this is also majorly misunderstood and overstated as the reason for lag problems. Having a turbo properly sized to your horsepower level to run in its efficiency range of what you are normally driving in is far more effective and less dangerous to eliminate lag than using compression to get there. What you commonly see, is someone who has a large turbo for a drag setup, but detuned for the street, so it is always running out of the range giving you a terrible powerband. In that case it would make sense to use higher compression to spool the turbo which is too large for the detuned street hp setup to prevent it from lagging all the time making it more driveable, and use E85 for the high horsepower setup when drag racing. However for someone who has no interest in competitive drag racing, that doesn't make any sense because you're always running like crap on the street. Anyone who’s owned or ridden in a Nissan Silvia with a correctly matched ball baring turbo should be able to attest, or any properly matched setup. I setup an SR20 in the past among other turbo cars I’ve built, GT2871R, INSTANT boost even with a very low compression(around 8.5:1), you have boost at a lower rpm than you would ever even be at racing. I’ve looked at hundreds of dynos of different turbo setups and compression ratios and found using the right turbo and boost level for your displacement is the most effective way to get a good power-band with low lag, compression may help but it's really not necessary with today's advances in turbo technology.

-Years ago before tuning advancements in recent years, almost all turbo setups on pump gas would have to lower compression to around 9:1 or less to make big power. The heat of making a high compression motor with boost would most surely detonate with any significant boost level and wouldn’t even make sense to make power that way. Today it seems it is more common to run mid compression around a 10:1 compression, some setups even higher. There is still a line somewhere you don’t want to cross on pump fuel with boost, it just has been pushed higher, and obviously if you are running alternative fuels, such as E85, that it will allow you to run even high compression.

-I realize it’s all about tuning, without a tuner you're not going anywhere, but I'm trying to get a feel for what kind of trade off I'm looking at (understanding the dynamics of it in all practicality). The characteristics of a motor that is going to constant acceleration out of corners generating heat over an extended period of time may be different.

-From what I've collected so far it seem going with either 9:1 or 10:1 forged pistons will be the best bet. The idea here at the end of the day is fine tuning the most indestructible and best power curve setup for that horsepower level.

Thanks,

 

might want to search for post like this, it has been covered.

those that have been down this path know how much "fun" it is to waste weekend at the track due to "issues" and "more issues" - always use trailer to and from track....

get really good a driving "slow" normal car before asking for more power.

but no one will listen so...

get a second car for daily
$20k might be a good amount to have in bank account when cars is ready for first "track day"
duct work
heat wrap
heat shielding
keep meltables far away from stuff that makes heat
spares, bring spares
fan for in pits when car is just getting off track
use cool down lap to drive like a old person... helps to not over heat when pulling in pits (stuff is hot but when moving everything will be working okish)

400whp on a stock engine, just saying...

 

I think you need to do a little more research into what an "scca build" is and what it means to "run scca" especially in regards to endurance racing. In my opinion, a street-legal turbo Honda enduro racecar is pretty tall order for a litany of reasons. Consider renting a seat for a crap can endurance race (i.e. LeMons or Chumpcar)?

 

I can't imagine what SCCA class this car would be legal for.

Try NASA PT

 

ITE would be the class for SCCA, kind of the catch all class.

It is like FB (wings and things) for formula cars.

 

I don't believe you can run ITE (if it still exists?) in the SCCA's Bracket Enduros, the only endurance races the SCCA has. I admittedly don't really know all the SCCA Bracket Enduro rules.
https://www.scca.com/pages/bracket-enduro

 

compression doesn't spool the turbo faster, if anything it will spool slower due t lower exhaust gases. you have alot more research to do.

 

SCCA events by me are in cramped parking lots. Turbo would suck. NA is best, and learning to drive a slow car fast is much easier and more fun then the inverse.

 

I guess it is all who puts on the race, most of the ones I have been to as long as you fit into a Tin Top Class in SCCA/NASA/PCA ect, they have a class for you. Also I will admin I have not raced competitively in years, track days are just less stressful...

 

SCCA Bracket Enduros are their own weird beast. You pick a time bracket that fits your team's* speed, you get penalized if you go faster, so instead of a class you have a time bracket. Nothing faster than ITR or E Prod.

As far as I know, NASA doesn't have endurance races on the East Coast. EMRA used to have one enduro on their schedule but I think 4 teams showed up for the last one so that's probably over. I think maybe the PCA does 1.5 hour enduros? But you have to have a Porsche. Which pretty much leaves Chumpcar and LeMons.

*Most endurance racing requires a "team" of drivers. So you either have to get some friends together to run or rent out the seats.

 

The car is only for recreation, I have another car for a daily. My goal isn't to compete in SCCA classes with this car it's about building a road racing setup to last (if it makes it easier just imagine you have a bunch of back-roads to race around all day, maybe you have access to nurburgring everyday, maybe your backyard is a racetrack, maybe you just dyno it over and over again every day for absolutely no reason, whatever you have to do, it doesn't matter).

All the other issues are a separate topic (suspension or classes or whatever, there's probably a separate post for that somewhere). I'm just talking strictly about building the car around that. I may use another car for actual competition but that's irrelevant to the subject. This post is only about the engine. The reason everything keeps getting posted over and over again on these forums is people can't stay on the topic, by the end it's a whole different conversation and it has to be reposted.

 

I'm confused. Your title says SCCA/Endurance racing but you state you are building a car for the street??

 

how much is your budget if you are serious?

 

Listen, I'm not here to blow up your spot or get into a H-T debate but you clearly have no idea what "road racing" is. You've posted in the wrong section of H-T if you want to have discourse about building a durable turbo Honda engine that can "have a bunch of back-roads to race around all day, maybe you have access to nurburgring everyday, maybe your backyard is a racetrack, maybe you just dyno it over and over again every day for absolutely no reason" (NONE of which are Road Racing / Autocross & Time Attack) and that's why this has gone off topic. To be blunt, you're either not asking the right questions - which is what I was trying to steer you toward in my first reply - OR you're in the wrong forum section. I'd still be happy to help you out any way I can if you're interested in getting started in autocross, time trials, or club and endurance racing.

 

It would be a street legal car that could be used on a Scca track (or road racing) from time to time recreationally (meaning built for that purpose as opposed to striaght line drag racing), not with the goal of serious competition in the way that your thinking but I may use another NA car for that purpose. The idea was that building a car that is accelerating, corning and braking running through the rpms for a more extended period of time would have different characteristics than a car built for drag racing. Not trying to be rude but it seems there has to be a hypothetical scenario for people otherwise you'll never get to the end of it. I thought it was pretty straight forward in the original post.

 

do you plan on putting a cage in it and installing the proper safety equipment for road racing? do you plan on doing wheel to wheel racing?

you're better off building a car around an already existing class instead of just making a hotrod just cause you want too...

sounds like you just want a fast car to do some HPDE stuff with.

here is what i would do

buy any civic/integra, swap in a B series motor if it doesnt have one already, put in forged pistons and use that pea-shooter turbo (GT28RS or whatever) and get a good tune and a nice phat oil cooler.

IIRC, that turbo is smaller than the td04 that was on the earlier WRX and that turbo is good for close to 300 WHP (thats all wheel, mind you) so making a reliable 250-300 whp shouldn't be an issue if you overbuild the motor.

i beliieve modified mag took an em1 civic (b16a2) and put in forged pistons with a gt30r equivilent borgwarner turbo and was making 500 whp on a non-sleeved block.