fongbros

HI, New to the forum. I have an 84 gsl-se former scca its race car. the car is still being used for track days now and gets towed to the track. It has open full dual exhaust all the way back to a very unrestricted muffler at the back bumper, cool air intake and an s4 manifold. Totally stripped interior (no dash, 1 aluminum seat, inner door shells cut, etc but it just doesn't have quite the oomph I would like. I 100 percent do not want to go turbo. I would like around 200-220 hp at the wheels. Will porting get me there? If so or if not, what is recommended? I do want to continue to use this engine. I don't care if the power band moves over because it is rarely under 4500 rpm at the track anyway. but I would like to keep it around 8k or so. Thanks for your suggestions,
Denis

Siraniko

iTrader: (13)

4 port bridge

fongbros

Please forgive my newness to the rotary. I have a 6 port 13b so which 4 ports would be getting work done on them?

Siraniko

iTrader: (13)

You will 12-A plates to make it a 4port

Jager

iTrader: (10)

Hello,

The previous posted is referring to using 12A irons into your GSL-SE motor. This will give you quite a bit of surface area to port.

Search around for various things like:

Beefy N/A
Any post by Hyperperformance2k
Kahren
SgtStinkFist

Some searchable options that will post you in the right direction.

Thanks!

peejay

You need to be a little clearer with the exhaust. You say it is "full dual" but you also say there is only one muffler.

Either way, you are not going to meet your power goal with the engine you have. You also are not going to see 300-350hp at 8000rpm.

23Racer

Peejay is totally right. Ypou need to go to a monster J port 4 port motor, a full bridge 4 port motor or a Periport. All 3 need revs to make it happen. Expect to be pulling close to 9,000 to make really good power.

The other thing to think about is to build a decent 4 port BP, bolt it in your car, get a good set of rear gears, like a 4:88 or 5:12 and lighten the car as much as possible. The weight reduction and gearing change will really perk up the car, even with the stock ITS style motor.

Eric

KNONFS

iTrader: (14)

In case OP is not aware of what the difference porting abbreviation means (or that the porting looks like):
Porting

peejay

I realize I may be coming across the wrong way. I tend to be blunt and forthright when it comes to tech matters.

The engine you currently have CAN be used as a starting point, but it will be just that - a starting point. The engine I have in my car started life as a GSL-SE engine - it has 12A end housings and a Series 4 rotating assembly ('86-up rotors is a must for high RPM, in my opnion - the rotor gear setup is far better and 2mm seals are more rev tolerant) but the eccentric shaft, stationary gears, rotor housings, and center housing are all GSL-SE

6 port end housings are just not very good for making power for a number of reasons. People have made power with them, mostly to prove a point or use up otherwise useless parts. But the same effort will reap much better rewards if starting with 4 port parts. Ideally you'd use a 12A center housing as well (intake ports are much larger) but then you would lose your fuel injector bungs.

I figure my engine is probably on about 260hp right now, which is anywhere from 170 to 300 wheel HP depending on whose dyno you use But it sure as heck isn't making peak HP at only 8000rpm. I'll have better numbers the next time I can datalog some full throttle runs.

fongbros

Thanks everyone for your input. So the suggestions seem to add up to - Use 12A end housings with a full bridgeport. I can keep my 13b center section in order to keep the fuel injection. 86 and up rotating assembly. My exhaust is 2 full unrestricted pipes that merge right behind the rear axle into a straight through muffler.
Also, I was revving 7k halfway down the long straights at summit point and NJMP, so higher gears in the back may not work just yet (until I get a higher revving engine).
I am guessing I will need a stand alone ignition. I am trying to use the stock ignition but my understanding is it kind of bobbles after 7k.
Also will bigger injectors be required?
Denis

peejay

With a bridge port, the GSL-SE injectors max out at about 230-235 crank HP. I used this setup for a few years and just lived with running static at the top end.

They max out about 10% lower on a stock/street port. Bridge and peripheral port engines have better BSFC at full load so they can make more power with the same fuel.

This year I de-restricted my intake setup and went to RC Engineering 1000cc injectors. Weather permitting, I'm going to hit the track tonight to see what my duty cycles are.

peejay

And the answer is, still making 230 hp at the crank. Trap speed is 103 and the track scale tells me that the car with me in it is 2650lb. At least the scale also says I have 1300lb nose weight and 1350 tail weight so I finally got a rear weight bias after all these years All it toon was leaving the tools/floor jqck in the back and installing a trailer hitch...

The strange part is, I'm still hitting 90% duty cycle at a stready 13:1 air/fuel ratio despite the significantly larger injectors. I wonder if the MS2/Extra code calculates duty cycle differently from MS1/B&G code. Or if my wideband has skewed and needs to be replaced.

t-von

iTrader: (8)

Why not just copy what Logan did with his Cosmo based side port? That street ported engine with shortened lim made 230rwhp.

https://www.rx7club.com/naturally-aspirated-performance-forum-220/make-230rwhp-streetport-13bre-n-818133/

pirsq

if you are willing to change up your combo ive done lots of development work on scca e-production cars and have an well developed expansion chamber exhaust stock 89-91 6ports have made in the 195+ range and street port motors so far as high as 235whp power band on pipe is 7200-11k+ only dynoed to 10.4k (power was still rising)but owner said it passed 11k so hard it he thought it would go to 12k if he didnt shift!on gsl-
se street port carb(36chokes scca mandated like 12years or so ago when car last dynoed)car was in the 195-200whp range and 12a (baby street port same chokes ) 170+whp

fongbros

So on my 84 gslse what would need changing in my combo? Street port and your expansion chamber exhaust? I imagine spark management as well. Want to keep f.i.

pirsq

if you are willing to change up your combo ive done lots of development work on scca e-production cars and have an well developed expansion chamber exhaust stock 89-91 6ports have made in the 195+ range and street port motors so far as high as 235whp power band on pipe is 7200-11k+ only dynoed to 10.4k (power was still rising)but owner said it passed 11k so hard it he thought it would go to 12k if he didnt shift!on gsl-
se street port carb(36chokes scca mandated like 12years or so ago when car last dynoed)car was in the 195-200whp range and 12a (baby street port same chokes ) 170+whp

KNONFS

iTrader: (14)

By keeping OEM EFI, you are limiting your power, hitting 200rwhp on the stock efi 6 port 13b will be extremely difficult, 220 rwhp, will be nearly impossible.

Start with an aftermarket ECU, like a haltec sprint re, it will suit very well. Then port whenever you have to open the engine.

lim_fc3c

iTrader: (4)

Could see my post and copy the build. It's pretty stout in the mid range. I'll dyno it soon, same car as well. I've personally made 160whp with the stock ecu with a tightened afm 850cc injectors s4 intakes. Now I'm on a completely different setup and way more power.

diabolical1

iTrader: (3)

are you limited by a class or anything? what's your ballpark budget?

fongbros

It races in opta batteries chumpcar world series so it really needs to look as stock as possible. Most likely my goal is unrealistic. I can do an s4 intake, bigger injectors and some pprting probably without drawing any attention to it.

KNONFS

iTrader: (14)

If that's case, you could try:

- 4 port front and rear irons (ported)
- Matching a 4 port lower intake manifold to the GSL-SE upper intake manifold (haven't look into this, maybe the hardest part)

Leave the injector and ecu stock, and see where that gets you.

diabolical1

iTrader: (3)

well, get a S4 or S5 engine and build on that. they are better starting points than the S3. better rotating assemblies, better injector layouts, better for high revs, etc.

given your car is a race car, i don't see the point to a street port, but given that you have to use the OEM intake system, i don't see a point to a bridge port either. people have bridge ported while using the stock intake and have claimed good results. personally, i still think it's wrong for a bridge, but i will accept and admit my inexperience on the subject. however, since i have to choose one, i would choose the bridge.

peejay

The GSL-SE intake manifold sucks compared to a Series 4. I have noticed major gains with that one change alone, several times on different kinds of port.

The S4 N/A is actually a really good unit. You'd have to be 100% on the ball to make 200rwhp with it, and we're talking maybe three people in the country could do it (perfect exhaust / perfect tune / perfect port / fresh engine with all new housings and tight seal clearances), but you can definitely hit 180.