How much power?

Time to rebuild the engine for my hopefully one day to be complete Group 5 Nissan 240. Initially I was going to just leave it stock, but that was a year ago when I had a decent stock engine to put in... Now that's in my daily driver/TSD car and the engine that came out is sitting in the rally car for "fitting" stuff.

So how much power should I aim for? How much can you realistically put through two wheels without ripping off tires ever stage?

I plan on using used tires until I win the lottery, 195-65-15 silverstones is what I'll be starting with.

The engine is SR20DET, my daily driver is putting a reliable 220hp (235ftlbs) to the wheels using the stock T25 turbo at 12psi.

I wouldn't think much more than 250rwph would be useful, would it? Fun, but not really useful!


I'm thinking CP forged pistons, ARP rod bolts, main studs, & head studs, good head gasket. The rest of the engine will be pretty much stock. I have a dual BB T28 turbo and injectors off the S15 engine. A friend of mine will od a custom ECU for me (he does lots for these engines)..

I'd like to build the bottom end strong so that I can use a bigger turbo and re-tune for more HP when it would be useful, like Targa Nfld... if I ever get there.

Does this sound like the right approach?

Suggestions?

-Martin.

Martin,

I'm biased because my mother is from Newfoundland and half my family is there.. but I've talked to a lot of people who have raced there and from what I've heard and seen it is THE event on this coast.

If you're planning on running it the story I hear is you will want lots of torque and top end.

Hopefully we both make it there one day

---

Andrew M
Onterrible
30ish

Sounds like we've seen and heard the same stuff... It's on my event calendar for this year! All I have to do is find the budget to be there!

If we don't make it this year, then we'l try for next...

-Martin.

You need the complete package. Brakes, gearbox, differential, and final drive are the hardest and least often done properly.

Engines are easy. Monster turbo only gets you more lag and a smaller powerband. Whereas a smaller turbo WITH proper tuning of fuel and ignition can yield better times in some situations. All depends on the nature of the event. If it's lots of tight twisty then this is beneficial. If it's bouncing of the rev limiter in 5th or 6th for alot of the time it's a different build philosophy.

---

Grant Hughes

MRWmotorsports Wrote:
-------------------------------------------------------
> Sounds like we've seen and heard the same stuff...
> It's on my event calendar for this year! All I
> have to do is find the budget to be there!
>
> If we don't make it this year, then we'l try for
> next...

Martin,

I have no hope of making it this year, but it is the only thing I want to do. I have too many other things to take care of first unfortunately.

I'm seriously thinking of heading up there this year to be a spectator.

---

Andrew M
Onterrible
30ish

NoCoast Wrote:
-------------------------------------------------------
> You need the complete package. Brakes, gearbox,
> differential, and final drive are the hardest and
> least often done properly.
>
> Engines are easy.

Grant, I agree with you. But, Targa Newfoundland is on pavement and you have a limited amount of tires for the event (I think 8 tires for 3 days of racing). So I don't think gravel/dirt formulas really apply.

Engines can quite easily be the single most expensive part of the car and you don't want to change your mind half way through a build.

Brakes are pretty easy. Throw on the biggest fucking brakes that are legal for your class and that will fit in your wheels. Gearbox is easy and can't really be decided upon until you have a motor figured out. Ditto on the final drive, spinning (slipping) your wheels all the time with a limited amount of tires is not an advantage on pavement.

After the engine I think suspension is the biggest problem for Targa. High speeds and rough roads. I think you would be best off with an "offroad" setup here.

Edit: my next post will have pictures

---

Andrew M
Onterrible
30ish



Edited 1 time(s). Last edit at 03/25/2006 02:42PM by hudson.

oy

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Andrew M
Onterrible
30ish

I'm not sure if your response is relative to my origianl question, or to Targa only...
Anyway I'm woring on the complete package...
I have all 300 ZX brakes, two pot rear, and 4 pot front calipers, vented 11+ inch rotors all around, twin masters, adjustable bias bar. I'm sticking with the stock transmission as I have several and $6k for a close ration dog box is out of the question, I know what the ratios are but don't have that info handy (they've worked OK for TSD for three years). I have a R200 clutch type 2 way LSD the ratio is currently 4.11 I'd like to make that 4.62 if I can find the ring and pinion at the right price. With a 4.62 rear end, 205-60-15 tires, in 3rd gear at 6500rpm it's 70mph, which seems to me like it should be useable, again it works good for TSD's. What do you think?

So how much power is useful for stage rally in rwd? Will the 250 that I'm planing be enough, or just a good start?

-Martin.

Hey Martin, some guys I know who build motors in Sweden say "after 235bhp you should be working more on delivery."
I watched in 1986 the 2wd GpB Celicas, and it was baaaaaaaad.
In 1987 I watched the GpA Stuprahs inline 6s and the 200SX factory V6, it was saaaad.
Even the GpN 8v Lancia ate them alive.

It wasn't the 4wd , it was the matched motor/turbo/box.

235 or 250 should be MORE than enough, the restricted GropeN Subarus as best have only a smidge more MAYBE..
And that presumes the geezers driving them actually open the throttles, and that is not a garantee.

But they goes pretty OK because the power is EASY, the box aint horrible, the final drive is OK

Your SR20DET is an excellent motor, just call for some CP peeeest-ons.

But listen: don't waste your time with some weeenie ass tiny POS Garrett T25 or some POS tiny Japanese POS POS.
All those little scrawny POS little things spin at somewher around 180,000 rpm to pass the CFM they do at NORMAL boost.


You want sumpin that spools NOW, yet in the unrestricted Gp5, will work good even as the motor revs up. So I have two words for you:
Ford Sierra Cosworth Garrett T3.

Don't argue, ask Kevin how it felt at 7 psi on his massively huge Volvo.

Paddy's getting one for his Xratty, and if you don't have one he will pull you badly.

Serious, its the coolest turbo in the known world.
If you wanted to go insane and shoot for 300 bhp-330 bhp, then you could add to the basic T# the T4 compressor housing, backing plate, and "50 trim" compressor wheel and have a quick spooling turbo that would pass the CFM and stiull only spin at 85,000.

Don't argue, don't ask geniuses in North America.

Post those ratios.
A 2.95 T5 would be sooooper bitchin

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

I was talking about Targa Newfoundland only.

---

Andrew M
Onterrible
30ish

Thanks John.

This was what I wanted to hear "235 or 250 should be MORE than enough"

the ratios are 3.321, 1.902, 1.308, 1, .759

These are what are in the boxes I have, that I will be using. I know they may not be optimal, but that's what I've got, and what I've got is what I'm using because what I don't got is lots of budget to buy lots of other stuff.

Same goes for the turbo, I have a dual BB T28, and 2 or 3 T25's so I'll be running the T28 and using the T25's as spares. I'm not going to argue about it, why would I? What you suggest just isn't an option. You're probably right anyway, you've been doing this for years.

I can't wait to run head to head with Paddy! I plan on kicking his ass no matter what turbo he's running :-)

I have to spend some money on the motor as it's wheezing like an old smoker. It needs new pistons, so if you could give me a price on CP I'd appreciate it.
86.5mm 8.5:1 compression was what I was thinking but I'm open to suggestions. I could probably go with stock sizes, but figured I'd go over size and bore the block vs honing... start off new instead of just decent

From what I've read the rod bolts need to be replaced, not sure about the main studs but figured while I'm in there why not. I've also read that the head bolts need to be replaced. I've always had good luck with ARP, but am open to suggestions.

Thanks...Martin.

Hey Martin, with those box ratios, keep the rear diff you have or go max MAYBE 4.3 just to compensate for the taller tires on gravel.

Sell those T25s to dogma pervs, and maybe sell the DBB T28 too, and with the million bucks you made selling all that crap, get a T3 and rebuild it and get the TURBINE HOUSING ONLY from JVAB in Seattle.

When Ford went tot the T25 on the last of the Escort Cossies, it was poiintless to try and make more than about 240 and turbo life suffered---too much shaft speed.

Yeas you probably want new bolts and not sure you need new main studs really.
Head studs maybe and a MLS gasket.

And maybe 8.0 comp, and more boost.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

MRWmotorsports Wrote:
-------------------------------------------------------
> I can't wait to run head to head with Paddy! I
> plan on kicking his ass no matter what turbo he's
> running :-)

Watch that smack talk old man, you'll need a lot more than 250HP to keep up with the Red Fury... ;-)

I have never driven a car that had too much power and that includs John Lane's 600 HP Gp5 Volvo.

Still 250 should get the job done.

DKB

---

In the long run reality always wins.

PAddy Wrote:
-------------------------------------------------------
> MRWmotorsports Wrote:
> --------------------------------------------------
> -----
> > I can't wait to run head to head with Paddy!
> I
> > plan on kicking his ass no matter what turbo
> he's
> > running :-)
>
> Watch that smack talk old man, you'll need a lot
> more than 250HP to keep up with the Red Fury...
> ;-)


We'll see which generation comes out on top when we both hit the stages young pup! Do you think you will make it out this year? I'm shooting for Black Bear.
We could do "PINKS rally style" :-)

-Martin.