Having a hard time deciding which path to take. All the exhaust work is done on car so now Im moving on to the engine. Decided to take care of intake next before heads and cam in the distant future. This car is not just for the 1/4, its for the street really. I know lt1 should give the most HP but at a higher RPM and I dont know if i'll ever use this arround town. Superram seems a nice balance between the two but is it really worth much over a built TPI (high flow manifold, runners, and plenum)? Keep in mind this will have stock cam and heads for now. Maybe cam will come soon. Or perhaps sdpc tpi with vortec and cam is the way...

 

Lt1 is By Far the Cheapest, So thats a magor consideration. If you Don't have Emissions in the area this or the HSR is probrably the way to go basedon cost alone.

Hi-Flow LTR is pretty much a joke, And Is incredibly expensive especially for what little you get.

Im going with the Superram, Because I live in California and Am sick of dealing with a questionably legal car. But that is just personal preferance.

 

Well with lt1, what is it going to do to the torque down low? And with super ram, how much will I notice before I change heads and cam?

 

With SR alone on a stock L98, friend of mine is running 13.4's in the 1/4 on stock programming.

Of course, thats in a 6 spd Vette but same idea.

As for the Lt1 Intake and loss of low end torque, people seem to get really hung up in this for some reason. It's not really a factor.

Ask anyone Who has actually installed a Miniram/Lt1 intake and they will tell you that it made vast improvements over the entire RPM range, and any minute loss in VERY low RPM torque was compensated for 100x

Its these same people who Worry about headers and everything else killing low end torque, who have never experianced them and don't know what they are talking about.

The only reasonable modification wich could have a very real detrimental effect on low end torque and resulting engine performance is the camshaft, as picking a cam that has a powerband higher than the rest of the components of your engine will kill your low end power and not give it back uptop.


But Selecting among the avaliable EFI Intake's, or headers, or heads ( providing you don't pick something with a 300cc intake runner ) Is not going to effect you THAT much.

Of course if you went Stabbing a single plane Carb Intake on a stock 305, Your gonna have problems, but thats a differant story.

 

So if LT1 is cheaper, why would you want Super Ram other then for emissions?

 

LT1 seems to build power in the upper rpm range while the SR builds it down low and throughout to about 6 something.

 

What Mkos Said.

the SR is still a LTR design, just with Bigger Runners wich allow it to build power higher. but its still empasizes torque.

the Lt1 intake IMO has more Horsepower potential by building Torque at higher RPMS, wich generally yeilds a better return than trying to build massive torque at Low RPM.

But then you gotta build a motor wich will hold up to the Higher RPMS, and you gotta spin it up there (converter, gears, ect )

For a Race motor this is obviously the way to go, On the street im Not so sure. Its fun, but speaking from experiance on a lesser level (262* cammed 305, NO low end torque) Its a hassle to have to spin 6g's before you go anywhere.

If Emissions was not a factor, Im pretty sure I would be doing the LT1 conversion, but as it is im sticking with LTR till i can fork up the 1.2G's for the SR.

Its a Small price to pay for living in CA.

 

OK, I own a 1988 GTA Transam also, and I am thinking of different ideas to modify my TPI engine, yet keep it as stock as possible, so nothing major. You said something about a high-flow manifold, plenum and runners? What exactly is that, and what does it do?

I'm just looking for ideas for my 350 cu. in. T.P.I.

 

Those parts are just replacements for the stock tpi parts. The manifold is a bit better flowing, Edelbrock makes one and TPIS makes the "bigmouth" manifold. Runners are also better flowing, SLP and AS&M seem to be most popular, people say AS&M are the best. All these parts can be ported for some better flow in addition.

 

My $.02.

Stay with a proven combo, the superram, LPE 219 cam, and some decent flowing heads, even ported stock heads will work with this combo.

With a heavy car like a GTA, mine weighs 3760 with me in it, you need more bottom end and midrange to get the car moving. Trust me, this combo works. I have the LT1 intake now, and the torque loss is noticable, but if you drive on the street most of the time, then it's better to stay with the superram. I couldn't hook the tires up with the superram to save my life with the stock suspension, so that's why I switched. I also hurt the old motor, so it was a perfect time to switch.

For all the crap you have to go thru swapping the LT1 intake on, you are better off with the superram or LTR's on a street car that is your daily driver. I have another car and a bike, so driveability doesn't matter to me.

 

Im leaning to superram now, and when I can afford it lpe cam and some 1.6 rockers. I've seen good results with ported stock heads so if I can find someone locally to do it that could be in the future. I already have sfc, and when the power gets too high I would upgrade lca to help tire roasting.

 

Not true, You just need to Gear and stall the car appropriately.

 

True, but this starts leading to worse streetability. It's all about trade off's.

MrNova, I would decide what rpm you want to shift at. This will also decide how good the car's street manners will be (b/c the higher you rev, the more gear and stall you need). You must also take into account that the higher you rev, the stronger the bottom end must be and that costs $$$. Also, reving higher requires a good valvetrain an in some cases rev kits or solid lifters=more $ and less streetability.

My opinion is the following-if you like shifting at 5000 rpm, keep the stock TPI and maybe get aftermarket runners. If you want to shift at 6000 rpm or so, get a SuperRam. If you want to shift higher than 6000, build the engine right, spin it to 7000 and put an LT1/MR on in and stick in a BIG cam. Whatever you want, get a good, well-matched combo and give it the right stall and gears and you will be happy.

 

What i don't get is heavy *** 4th gen TAs with an LT1 can be streetable 11s. I don't understand why the same thing wouldn't work on another car? Maybe i'm dumb?