B17aTrbo

Sorry for yet another sc61 thread but I am currently possibly in the market for another turbo for my setup and since it is an expensive endeaver I'd like to make sure its a good choice...

I know it seems to be the bandwagen choice for turbos and some seem to hate it because it is so popular. However from what I've read in the archives it certainly has merit...

The setup is pretty basic...
B17a block (1678cc's) bored to 84mm which with my calculations makes it right at 1.8 liters (1804cc's), benson sleeves, cp pistons, crower rods...etc. etc.

I'm switching back from the ys1 ls to the ys1 gsr here's the ratios...
1st: 3.31:1
2nd: 2.11:1
3rd: 1.46:1
4th: 1.11:1
5th: .088:1
Final: 4.40:1

[edit] factory valvetrain for now and using factory 8k rpm redline [edit]

Fuel consist of 880's, 255lph and hondata s200b...

The car is a street car but I don't drive it everyday...I'd like to have it put out good power (450+, mid 11s 1/4 mile 120mph-full interior'd DA)...right now I have a garrett 54 trim .63 a/r stage 3 wheel and I don't *believe* will get the job done, of course if it WILL then I don't need to upgrade and that would mean I can save mad loot!

Also something to consider is I don't mind running 20-22psi on my current turbo if need be to get to my goals...

Anyway sorry so long but like I said I work hard for my money and want to make this project turn out decent, what better way to make sure than to check with H-T?

B17aTrbo

9.2:1 compression

B17aTrbo

trbob16a

First off you can do mid 11's without 450+ so you need to figure out which is your real goal. Beyond that, I say you should put it together, tune, and make a decision after that. A bar on street gas should be enough to keep you happy for quite a while.

B17aTrbo

Well I'm not too familiar with what it takes to do what hp wise compared to quarter mile times...

I guess I just always figured that cars running 10s had 500-600 hp with big slicks and wheelie bars hehe...

What kind of power do you think I'd need to run it full weight (probably close to 2800 lbs. With me in it) mid 11s?

Yes I guess I could put it together and see what happens...thought maybe someone had some insight as to if it was feasible to get it done with the current turbo I'm running, if the sc61 would be overkill, or if there is something in between that would be better/best...

TurboTegB18c

You guessed pretty right, with about 2800lbs, you would need around 430whp or so to run mid 11's. Look in sig for my times. Paul

TurboJesse

I would say if you can drive good and your car is setup right, you could go mid 11's with 375-390whp @ 2800lbs

Quick 200k Mile Motor

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B17aTrbo &raquo;</TD></TR><TR><TD CLASS="quote">right at 1.8 liters (1804cc's)
I'm switching back from the ys1 ls to the ys1 gsr here's the ratios...
1st: 3.31:1
2nd: 2.11:1
3rd: 1.46:1
4th: 1.11:1
5th: .088:1 &lt;---------- @ 80mph you are near 5000 rpm in 5th
Final: 4.40:1
</TD></TR></TABLE>

Not many remember that tranny because its hard to find.
I however, can't forget! You said it was a street car, right?
With the power goals implied, Id say you'll only have some traction in 4th..
and thats from feeling the kick of the SC61 on a gsr, and having that tranny for quite a few years. On the other gears, as boost kicks in.. you'll find yourself trying to gain traction by feathering the throttle a lot (which is bad with boost, you want full tip in).

The only reason of running that tranny with that amount of power would be for the expansion of the slicks as you near the trap. But its a street car.

B17aTrbo

Quick 200k motor: The car is a street car but at the track I will be swapping the street tire setup for some 24.5x8 slicks...

I was hoping that I could finish @ or around the top of 4th gear...probably not tho

It is a street car that I would *only* race if it was a new cobra, corvette or something fast of that nature.. and never from low gears!

B17aTrbo

Turbotegb18c: yeah your times are what I'm looking for...

I don't necessarily need to be the fastest at the track because I don't have the kind of money it takes to run with the big boys! A few years back I might would be like "I got a chance this year" but now 11s is soo common place...

I see you are running the sc61 yourself...do you feel like you were pushing the turbo a lot or is it something you think you could have done with a t3/t4 54 trim?

DLB1994

what intercooler and manifold are you running and i don't think the 54trim will make not much over 400whp

the sc61 is a good turbo but i think people jump on a turbo of that size that don't ever plan on make 550-600whp

but you wont be mad if you get the sc61, you will just have a big big big change in lag

Rod Short

At 2,800 lbs, our calculator shows you'd run a 11.39 at 119.7 with just 375-hp at the wheels. In real life, however, your ET can vary wildly depending on a number of things. MPH is a much better indicator of what kind of hp a car has.

With a 1.8L, the SC61 with the T350 76 trim wheel is the best match for that engine. That will support up to 630-hp at the flywheel with proper tuning. If you figure a 20% loss thru the drivetrain (worst case scenario), you'd be looking at 504 at the tire. In round town driving at moderate boost levels, figure on 400 at the wheels.

If you don't mind 20-22 lbs of boost, a smaller turbo would work and spool quicker for you. An SC60, for example, would put you in the neighborhood of 464 at the wheels while a SC44 would be about 10-15 hp less and be a lot more fun to drive everyday.

I know you're engine is modified, but when you get down to the 1.7-litre range and lower, I believe you're getting into a gray area as to whether or not a T3/T4 is too large for a street engine anyway. The smaller line of SC turbos tend to make a lot of sense here. Racing, however, tends to throw a lot of that advice out the window.

Everything's a compromise. It's always a challenge to find something that will do both well, no matter whether it a turbo, blower or whatever.

Rod Short
Sales Manager
Precision Turbo

B17aTrbo

Dlb1994: well I thought about the lag and I noticed that a lot of b18s are getting full boost between 4500 and 5000 rpms which would be ok for me...

I figure since its now a bigger bore than before and I went up from about 8.2 to 9.2:1 compression that it shouldn't be TOO much different than before...

DIRep972

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">With a 1.8L, the SC61 with the T350 76 trim wheel is the best match for that engine. That will support up to 630-hp at the flywheel with proper tuning. If you figure a 20% loss thru the drivetrain (worst case scenario), you'd be looking at 504 at the tire. In round town driving at moderate boost levels, figure on 400 at the wheels. </TD></TR></TABLE>

Rod those #'s are definitly conservative. I have seen 530whp @ 24psi and 520whp @ 25psi, both on SC61's w/ T350 turbines, and both cars had more in it but were limited to that amount of boost by the wastegate spring.

I get this question all the time on pm; "do you think the SC61 is too big? will it be too laggy?" "will I be faster with a smaller turbo? I don't want too run too much boost." etc etc...

What I always tell people is that you have to size your turbo to the owner. It really depends on what the owner wants out of the car.. Sometimes people want time slips at the track, sometimes they just wanna win races on the street, and sometimes they just wanna hit a big dyno #.. Its all about compromises.

On the track, your powerband is pretty predictable. You rev it up at the line, the track is sticky, you luanch in 1st, you spin it to 9k, it falls to 6k, you rev it to 8800 in 2nd, it falls to 6500, you rev it to 8600 in 3rd, it fallas to 6800, and you rev it to 8600 in 4th. So what you want in this scenario is a turbo that is going to maximize your power between 6-9k and have good response off the line and respond good between shifting... I don't think there is a better turbo then the SC61/GT35e for a 1.8L GSR motor that wants to do this type of racing.

On the street, your powerband is not so predictable. Chances are your on street tires, and if your racing from a stop your going to have to leave the line about 3500rpm's. You don't want a turbo that lags to 6k cause by the time you get moving the car your racing will be so far out in front he will have shut down, tapped the brakes, and declared you the first loser before you even reach his back bumper. But then racing off the line isn't the only thing you do on the street, what about when your cruising at 40mph, 50mph, 60mph, 70mph, 80mph on the highway and a vette rolls up next to you? what are the chances that everytime a car rolls up next to you you will be at the perfect mph and in the right powerband to race them? Chances are very slim. So what you want is a turbo that gives you a very broad powerband, that will allow you to race and win in a wide variety of situations. The SC61 can do this, but I think there are smaller turbos out there that can do it better. You just have to sacrifice peak power for a broad powerband.

B17aTrbo, I think you fall into the track guy category. because you have a time slip and mph goal. I think your current turbo can achieve your goals, but you are going to have to push it really hard. 450+ on a 54 trim is going to take some luck or a ton of boost. The SC61 would fit you perfect. It will make the power you want at the boost you want, spool up good and respond great in the conditions you will be racing. Plus it will leave more potential if you decide to rev it higher later and turn up the boost..