Brand new to the board here & I'd like to hear any comments, opinons, &/or ideas about any of the following:
I just bought my uncle's totaled 95 Trans Am 6 speed and will soon start pirating parts from it for my stock 89 Formula 350 with 3.70 geared 9 bolt. I plan on sending the intake, fuel rails, and injectors to be converted for use on my L98 since the LT1 seems to be a hassle to install due to the front bracketry (esp the A/C which is a must here in GA) and using my stock throttle body, wiring, and TPI computer with maybe a chip change. I'm also planning on using the seats, console, and rear wing which all appear to be bolt-ins. I'm thinking that with the LT1 intake swap my stock L98 will make almost as much power as the LT1 does. My dual cat L98 is rated at 240 HP @ 4400 rpm / 345 TQ @ 3200 versus 95 LT1's 275 HP @ 5200 rpm / 325 TQ@ 2400 rpm and I think the LT1 intake & it's 24 lb. injectors, my L98 stock 48 mm TB, distributer, & compter should be about enough to make up for the difference in the HP & the RPM advantage the LT1 has. Also, my 89 L98 cam has more duration than the LT1 cam and should give me a broader power band with the same intake right? I plan on installing 1.6:1 rockers to make up for the difference in lift. (Maybe a ZZ4 cam later on).
I love the torqe my TPI motor makes, but when I test drove the TA today - wearing safety goggles to keep the broken windshield glass out of my eyes - it sure felt nice to be able to go past 4500 rpm & still feel the engine pulling. I never revved it past about 5700, but it felt like it would have went higher.

Let's hear it everyone. I haven't mastered the search function here yet, so I hope alot of you respond. Now turn me loose searching on eBay and that's a different story!!
Thanks, Jason

 

P.S. I forgot to mention, I've already read the T56 swap F.A.Q. and visited LT1intake.com. I just posted this to hear the opinions of some of ya'll about my proposed mods.

 

Longer duration doesn't broaden the power range, but more moves the power to the end of the power band instead of middle/center.

The lt1's power comes from many places other than just the intake. Higher compression, better detonation tollerances with reverse cooling and aluminum heads. Less parasetic losses to waterpumps distributors and other things that changed since the GEN1 small block, and the port design and angle of the heads. Dont think that a simple intake will make up the difference


With taht being said the LT1 *IS* in my opinion the way to go, if you're going all the way (change your cam and either port or swap your heads) because in a performance environment the LT1 intake is going to flow similar to the miniram which undoubtedly turns some of the fastest times out there (we'll see if that changes with the up and coming HSR when people actually start flogging them)


Your plans seem to be in the right direction, just dont expect a miracle to happen with simply changing an intake.

 

True the LT1 has a higher compression ratio, but that isn't really much of a power adder in this instance because you are comparing iron heads with 9.3:1 CR vs. aluminum heads with about 10.25:1 CR. An aluminum head has to have at least an additional 1/2 point of CR just to make up for heat loss when compared to an equally well flowing iron head to make the same amount of power. That is why the L98 F-body & the L98 vette engines make about the same power even though the vette L98 has about .5 more CR and aluminum heads. I have heard repeatedly that the iron L98 heads acutally flow better than the aluminum ones!! The tiny HP rating advantage the vette has is due to better exhaust & air intake path as compared to the F-body (plus the fact that GM is going to rate it's Corvette higher for marketing purposes).
With that being said, the LT1 heads do have better ports as compared to the L98 heads (iron or aluminum) so the LT1 longblock should still make more power vs. the L98 with the same (LT1) intake. I doubt that it will be very much more though.

 

There are thermal inefficiancy issues with aluminum heads but I think that they're exadurated by the whole.... yea you need a bit more compression, but you can also run more timing, so there's another trade off, and comparing apples to apples (same car) the aluminum heads are lighter so thats quicker et's (regardless of power) but if you spend enough time at the strip, or if you've ever had an ET goal it becomes oh so obvious oh so quickly how the little itty bitty things are the things that add up. Like a better fuel management system is another thing I hadn't mentioned, the addition of map + maf and i believe lt1's also had 2 02's? and LS1's had 4? that last part i might be wrong on but anyways, it all adds up, the LT1's power in my opinion is from cutting down on parasitic losses, and adding the new intake port design combined with the well flowing intake.


When you're swapping intakes on an L98 you're not stock any more and you can reasonably assume that person X is trying to gain performance, so the addition of the LT1 intake is usually to feed higher than stock runner heads, or a larger cam. Rarely would the intake be changed to an otherwise stock L98, and if/when it is/does happen you're deffinatly not going to end up with an LT1 power curve.


in a performance environment though, the lt1 intake makes all the sense in the world

 

I see you live in GA also...if you do decide not to use the LT1, I might be interested in all or part of the LT1 stuff.

 

by putting the LT1 intake on a stock iron L98, your pretty much going to change your numbers to the LT1 numbers. the cams are almost the same and the stocker LT1 heads arent exactly bad as*.

notice i did say pretty much.

 

Stocker lt1 heads aren't bad ***?

I can't even count the 12 and some 11 second N/A lt1's with stock heads.

 

I vote to keep the LT1. Initially more expensive, but a lot less hassle in the long run. Look into the LT4 Heads, intake, and the HOT Cam. There is a guy on this board who swapping his LT1 into his Third gen now ... Zephyr I believe. If you have the technology, use it!

 

We just swapped in a complete LT1 into my friend's 89 IROC (using DFI to work everything). It pulls really nicely up top. No times on it yet, soon as we get some, i'll post them.

 

How do you work DFI with Opti?

 

Accel has a specific DFI setup strictly for LT1s that work with the opti