LT1 ATI Twin Intercooler Limit

I'm looking for people who have personal experience with the twin intercooler kit for an LT1 from ATI.

What is the limit of these intercoolers for FWHP/RWHP before they become a serious restriction and are no longer viable?

For LT1s which use the smaller twins, I've heard around 12+lbs. of boost is the limit to where they're effective. Although in talking with ATI they wouldn't agree. I guess the best way to know would be to monitor IATs. I should have a pretty good idea on this in 2-3 weeks.

Sounds like i have the same setup 396/D1/AFR/9".... With a so-so tune my car made 672 rwhp @ 12 psi....

I am looking to change the blow off valve and raise the boost to 15 psi (if i can).

I have seen 8#'s on the D1SC pushing 500 RWHP come severely close to detonation with the twin intercoolers that come from ATI for the LT1 kit. Personally, I would like them to make a larger kit like what they make for the LS1's.

IMO, anything more than 500 to the wheels or 8#'s, and I would look at getting a custom FMIC. Thats what I did.
http://i6.tinypic.com/1z5ouj9.jpg

The LT1 twin I/C setup will support sub 10 second performance. Any twin setup is admittedly a compromise due to packaging which is the reason they were developed for the Fbody.

Keep in mind when using a chassis dyno that the twin setup will not cool very effectively due to a lack of any substantial airflow available to them. They will perform much better when used on the street or at the track. Get a data logging solution and measure your IAT when actually driving, also make note of the ambient temperature to gauge effectiveness of the system.

I have never seen a good twin/fmic comparison of actual IAT and performance with no other changes. Many people feel the fmic is better on the Camaro as it looks as if it would be, but actual real world results from the conversion are lacking.

I disagree. For the LT1's, I have seen more than once where a mild amount of boost was too much for the twin IC's to keep cool before detonation was an issue. After changing to a FMIC the IAT's were much lower, and kept things much further away from detonation. BTW, this was all done by monitering things on a laptop while driven on the street, not on a dyno.

Is this power being made with pump gas?

What pulley combo are you using to arrive at the 12lbs?


Sounds like i have the same setup 396/D1/AFR/9".... With a so-so tune my car made 672 rwhp @ 12 psi....

I am looking to change the blow off valve and raise the boost to 15 psi (if i can).

I did compromise with the twins over a FMIC due to not wanting to cut up the formula nose. I'm hoping to see just how much the twin high flows will take in the next few months... A T-76 Q-trim will be feeding a little 383 cube LT1.

We'll find out what the limit is soon hopefully (if my Lunati Pro Mod rods will ever come in) as my 383/TFS/D-1SC setup will be seeing everything we can throw at it through the twin high flows. There's really not a FMIC option that's acceptable for me on the T/A's, so I'm going to do the best with what I've got to work with.

Widh twin IC and maxed out P1sc 12-13psi (dynoed 600rwhp) IAT went from 90-> 145 degrees on a 1/8 mile runn (165 on a 1/4)
Now widh a max reved F1 17psi, 4" obx FMIC and a small shot of alky IAT went from 85-> 95 on a 1/8 mile..

Widh twin IC and maxed out P1sc 12-13psi (dynoed 600rwhp) IAT went from 90-> 145 degrees on a 1/8 mile runn (165 on a 1/4)
Now widh a max reved F1 17psi, 4" obx FMIC and a small shot of alky IAT went from 85-> 95 on a 1/8 mile..

Sounds like they're doing their job adequately on your application.

Now widh a max reved F1 17psi, 4" obx FMIC and a small shot of alky IAT went from 85-> 95 on a 1/8 mile..


Sounds like they're doing their job adequately on your application.

Looks like they switched to a 4" OBX FMIC to get those results.

Jerry

There's no doubt to me that a large FMIC is superior. Just look at the surface area available for heat exchange. I'd like to know how much of a rise in IATs would be considered acceptable. This would give you an idea of when its time for a bigger intercooler.

I always had the idea of making some custom air-scoops for the twins. ATI just supplies a straight piece of rubber which bolts onto the back of the coolers.
They twins fit real nice. Currently I have the vortech air-water intercooler which works better, but you have the aftercooler core sitting right over the driver side valve cover and headers, that's what I do not like about it. Pain in the but when you want to service the valve covers or get to the headers.