Levi Kragt

'88 700r4.
58mm throttle body
TPIS bigmouth
ported plenum
siamesed slp runners
28lb injectors.
113 heads.
pace setter headers
pypes performance exhuast
stock cam i believe.
it runs, it drives, but not amazingly, misfires are common. idle is erradic
how much do yall think ill put down after i drive it up to tpis for a tune?

bjankuski

My guess is 240 rwhp. If you put the stock injectors in you probably would not need a tune. Stock heads and cam with a maf car should be ok. Why is it missing? If the timing and firing order are correct with no mechanical issues, it should not miss.it will be running on the rich side now, maybe that is why it is missing.

GREGGPENN

Brians guess is as good as any...which shouldn't be your main concern. Mixed reviews on TPIS tuning though they may be as good as any in your area. Have you you asked them what you need to tune? (You may need some add-ons for the computer?)

I agree with Brian about his comment on injectors. 28lb is significantly bigger than stock AND could have been a better selection. With the RIGHT selection, tuning might be negated (though I'd also point out the 58mm TB is an obstacle too). A larger TB wasn't necessary, doesn't add power, yet changes the tuning parameters. If you go back to stock size injectors and the stock throttle body, you may not need a tune.

If you don't, buy a couple of things from Moates, change a few parms, and see how it runs. You'll learn something and spend money on something useful down the road. Certainly a better purchase than 58mm with 28lb injectors. One thing many people don't realize is: L98's fire injectors in batch mode (once per cam revolution). If enough "power" is needed, double-fire mode is engaged where it fires once per crank revolution (twice as often). That means stock 22/24lb injectors can act like they are in the 40's. PLENTY OF FUEL IS AVAILABLE with stock-sized injectors! Once you go changing injector size, tuning becomes necessary.

How well the runners are ported will factor into your numbers. With your build, torque is as important (if not more than HP).

vader86

Probably 240-245rwhp.

Levi Kragt

TPIS is the only place in the my area that will do it. I do have the stock injectors. The previous owner was the one who swapped the injectors for 28lb-ers. I also questioned the 58mm decision as well, so I bought an oem throttle body, broke it trying to regasket it. I want a tune because I've always wanted a car Dyno'd but never could until now. Right now I've got to regasket everything above the intake manifold, vacuum leaks from runners and throttle body, both where they meet the plenum do you guys thing that could cause my missing?

Levi Kragt

My goal is 300whp, what needs done for that to be the case?

aklim

I wonder if Hitech Motorsport will still do it? I had it done there in Elk River a few years ago so not sure.

aklim

How about a cam and an intake that is matched for that cam and long tube headers, correct size injectors, followed by a dyno tune?

Levi Kragt

So you think I should put the 22s back? What's wrong with the tpis big mouth? I'm looking for a cam with great drivability and idle quality. I'm in the Des Moines Area so elk River is basically the same as TPIS in terms of distance

aklim

I think at 95% duty cycle you can pull 350 out of 22pph injectors.

What I wonder is whether you are having a whole system or parts of it. I can have an Accel TB, Different runners, erc, etc. Might be nice to find a system where the exponents have shown that their combo of heads, intake and exhaust is right. That when matched with a cam

Levi Kragt

That that makes a lot of sense, I figured my combo of SLP runners into a tpis bigmouth was common, I don't intend to put heads on the car. I've got factory 113s, (don't recall if I've said that already) I guess I'll throw those 22 lbs back in. Haven't heard it run with the stock injectors. Hopefully my bouncy idle goes away.

GREGGPENN

If your OEM injectors are original (30yrs old), I wouldn't be inclined to reinstall them. Stock injectors weren't "made" for current gasohol levels. They tend to break-down with age/miles. Jon @ FIC could get you an equivalent (new or rebuilt set of modern injectors -- if interested). However, if you have to spend money ANYWAY, there's no reason getting your current combo tuned is a worse option. If your new 28lb injectors are new/good and you are sure of it AND you don't have an OEM throttle body, go ahead and tune it -- as is. The bigger ones won't hurt....when tuned properly.

The combo of a big-mouth, SLP headers, and headers isn't wrong, bad, or even unusual. He's just trying to coax you into a cam -- which would help "wake things up". OEM version of your car is right around 200-205 on the rollers IIRC. Basically, they are just saying you'll gain about 35-40 hp...basically about 50/50 due to intake/exhaust upgrade. Again, the larger TB doesn't really help on your combo.

TPIS is known for many things and they have tuned lots of cars. I haven't read about problems recently, so don't worry about their tuning ability -- ESPECIALLY if you don't want to learn on your own. Or accept help from a member here. FWIW...I'll add that TPIS would be THE shop I'd send 113 heads to...if considered porting. You'd more than double your gains with ported heads and a cam....with even more smiles/week. 113 heads aren't a bad option for porting with a longtube setup.

Would be nice if you were sure about the cam/heads combo as it sits now.

Levi Kragt

That cleared alot up, thanks to everyone so far. Glad to hear I can have these heads ported vs getting new ones. How do I figure out what cam I need? I know the old adage "you ask 20 people and get 25 different answers" but now you guys know what I'm running, with that, i intend to keep the heads that are on it. Have them ported. What will give me that 300 whp I so desire?

GREGGPENN

Lingenfelter superram cam would be my pick with fully ported (CNC?) and would get right around 300rwhp. It's 219/219 with about .550 lift IIRC. You could go with a big more exhaust duration is you like a little more bubba-la-bubba-la sound.

I'm not totally sure but I'd think the 113 heads can be modified for that much lift (by TPIS). After all, I'm fairly sure Lingenfelter used those heads with that cam to build track cars (with his superram intake) back in the late 80's/90's.

That said....TPIS would steer you the right direction for a cam with their porting options. They may have 2 or 3 "stages" of porting which would dictate the cam (especially lift).

FWIW, I hand-ported the heck out of my SLP runners for my 383. Took hours and hours and hours but I did it using only a drill/extension/burr. You might want to give that a whirl too.

Levi Kragt

I'll have to see what mine look like I haven't taken the intake off yet. The previous owner said he ported the hell out of him but there's no way he did that much I'll keep you guys posted. An interesting note. I've driven this thing thousands of miles with it running like this, it doesn't miss when I cruise, but when I stab it does. Thing has taken me on long trips just fine too. Had the tranny rebuilt with Superior shift kit. This my second Vette. In the infamous guy in late 2015 who bought a c4 at 16, got majorly **** on. Thing was carbed, TPI is so much better.

Space387

Your symptoms sound like poor fuel management. The difference from your stock to current injectors is a gain of 22% fuel flow, this it important. When at idle or very low RPM the computer is relying on the programmed tables, same with sudden acceleration( TPS movement). This is not adjusted by your MAF or o2 sensors there for it is using the same pule time ( and giving 22% more fuel than expected). When you are cruising the aforementioned sensors are used with the BLM system and whats called open loop mode allowing the engine to tune for optimal conditions under cruise. The fix is 100% you need a tune. Even if you just got teh parts and only change the parameter for the calculated injector size ( from 22 to 28) the car can figure the rest out to get you closer to tuned. You will still have to make fine adjustments but this will put you a lot closer. I tried the same thing on my LT1 a few years ago with a set of 30lb injectors and it didn't like it at all.

aklim

Stock SIZED, yes. Get a reman set. If you want to test it out, use the old ones. If not get reman ones. Cheaper.

aklim

Note, the stock ones are older Multecs which means they don't agree with ethanol. That means you are limited to pure gas so you would have to only gas up there. Quite a PITA so get FIC to set you up and you should be fine. For a test project, sure. For long term, I wouldn't but that is how much inconvenience would you put up with

aklim

IF you like Myron C, ask him what he recommends for your setup. Remember, it all has to work as a system and not bits and pieces. After all, he has to tune it so he should have a say.

aklim

YUCK. I'd definitely give TPIS a chance to look over these things. Seeing as how his attitude is "Bigger is better" as can be seen with the injectors and that he left it standing with these issues, I can see he doesn't know what he is doing and does things "as the spirit moves him". Let them see how good or, as I am suspecting, how crummy a job he did. Kinda sours me from modified vehicles since I don't know what you did and how.