Steves LS6

Hello. I am looking to purchase an L98 for a project I'm working on and I have two motors I am looking at an 89 and an 91. From what I have seen the 89 is MAF, slightly bigger cam, and the heads are different. Is there any benefit with going in with the 89 over the 91 or 91 over the 89? Any help would be appreciated.

aklim

Speed density is harder to work with when mods come in since it doesn't adjust as well. That said, once set up, life is good. What do you want this car to do? If you are building it and trying different mods, I'd go MAF. If you are doing a "set it and forget it", I'd go SD.

Steves LS6

I already have SD in it. Probably just do a cam upgrade and headers.

aklim

Why? With the L98 intake, you are hobbling yourself. Also cam changes would be only SOTP, or as I like to call it, imaginary. I'd do intakes, headers cam and fluff the heads. After that, dyno tuning.

Tom400CFI

Say what? Cam is the single biggest change you can make to a motor, other than forced induction. One car I had, I did a cam & lifter ONLY swap, and dropped a second off my 1/4 mile time. No other single part will do that -especially for the price.

aklim

Yes, perhaps I should explain what I was saying. A more radical cam will require tuning and the intake is going to run out of steam at about 5000. So is it good to change the cam with a "computer friendly" cam? Now if you change the intake and the cam and tune, I agree. Just a "computer friendly" cam would be a waste.

How did you get a second without the ECM being tweaked? I did intake and headers and it ran but never right. My 74219 cam would run but not smoothly when we had the stock intake on.

Tom400CFI

It was an '83 TA so it had a feed back carb. It still had a speed density system to fine tune the primary side of the carb...but with no tuning at all; jets or chips, it ran fine and went 1 sec faster.

For sure a speed density car could use a tune after a cam swap like that one.

aklim

OK. I know very little about carbs and when my lawn equipment has fuel issues, I call the "Mobile Repair Guys" and they bring their trailer with the parts and fix them for me. I only change oil, plugs and blades, if they have them. Fortunately I sold all the powersports stuff with carbs so the 2 ATVs, Jetskis and wife's trike are all EFI as are all my cars. You couldn't give me a carb car.

I would imagine so unless the cam is close to the OEM which is a waste of resources.

Steves LS6

I know the TPI intake doesn't flow that well above 5000 rpm. I forgot to mention that the intake was going to be ported and I am trying to keep the car looking factory. The person that I am having help me out has built numerous TPI motors and has tuned even more cars that have already been built. He's telling me that the TPI will give me what I am looking for. I am not looking for all out power just a little more pep.


Right now I'm looking for a motor and of the two I have in mind ones an 89 and the other is a 91. Let's leave the MAF/SD, and cam arguments out of the equation. Are the pistons the only difference between the years of the motors? I have been looking at 1/4 mile times and the 89's and 90/91's run about the same with smaller gears. Are the 90/91's underrated?

Steves LS6

If you had an LG4 I can see that easily happening.

Cjunkie

Yeah right cam only swap 1 sec uh huh sure. Everyone in the world would be doing that if true.
Just 1 more GM guy 'cam only' line.

Steves LS6

It's possible. He didn't mention if it was an LG4 or L69. If it's an L69 I don't see it. The L69 had an aggressive cam ( I dont have the specs in front of me but it was more aggressive than the L83 cam and it might even be bigger than the 85-87 L98 cam) in it and if I remember correctly an L69 car ran mid 15's and an LG4 car ran high 16's on a good run. L69's also had freer flowing exhaust, 3.73's and the Trans Am had the "ram air" scoop that ducts the air into the air cleaner. If I remember correctly this "ram air" was part of the WS6 package so it also came on the LG4. The L69 package is good for ~1.5 seconds. What would the cam alone do? He didn't mention any cam specs either.

Tom400CFI

Are you kidding? I hope so.


It was and LG4. The cam swapped in was not big. IIRC it was in the 2-low teens range. 212/218ish? Still idled like stock, still got stock like gas mileage.

Results could easily be reproduced. Wait...*I* reproduced that result in a LU5 (CFI) TA, years later.

How many other "GM guy cam only lines" are there?

Tom400CFI

This LG4 went 16.1 stock, 15.1 cam & lifters ONLY. (obviously, lifters are part of a flat tappet cam swap, and no contribution to power -I only mention them to be forth coming about all the parts that were replaced) I think I replaced the timing chain too. Probably a few gaskets.

You're right that the LG4 came with the cowl hood. All LG4, LU5, and L69 Trans Am's had that hood. Some Camaro's had a cold air hood too, but I THINK on those it was only on LU5's and L69's.

Steves LS6

Those a great times for an LG4.

In 1982-1983 LU5 Camaro's had a fiberglass hood with functional flaps. I am not sure if in 83 all Z28's had fiberglass hoods on them and they switched to steel in 84. L69 Camaro's had the dual snorkel air cleaner with the giant ducts and the hood flaps were non functional. In 85 both the IROC and TA had the dual snorkel air cleaner on the L69. They supposedly made some L69's in 1986 but as far as I know those are unicorn cars.

Tom400CFI

Thanks. I was pretty embarrassed by the stock 1/4 mile times, but pretty proud of the change from the cam. Back then, darn "fast" street cars were running 13's, so what ever LG4's should have run, I knew that 16.1 wasn't very good.


Huh....I have yet to see an L69 TA with a dual snorkel air cleaner. Every one that I have seen had the single w/the cowl hood, like this:



I guess an '85 would have dual snorkel b/c they didn't have the cowl hood anymore, after '84.




.

Steves LS6

In 85 they used the same air cleaner as the camaro. 85 L69's are rare especially trans ams. There was an L69 Recaro on ebay about a month ago. They pop up from time to time.


Enjoy!