Just curious. I am thinking about a blower for my LT4 trans-am. Stock bottom end putting out 455 ponies.

I don't drive it hard, probably get on it like 3 times a week. Want a blower just for fun and to see what 600+ horsepower feels like.

 

You'll probably get more answers on CamaroZ28.Com since most of those guys are into LT1/LS1. But anyway, is the car a true LT4 or a LT1 converted to a LT4? I've heard the true LT4 has a stronger bottom end than the LT1. Some guys who convert their LT1 to a LT4 say it was a bad idea because they end up spinning bearings. So the LT4 will probably last longer. Either way, I would say its kind of a grey area, nobody can say for sure how long it will last. Best bet is not to run too much boost since thats a high compression motor, 6-9 psi max. As long as the motor was properly maintained over the course of its life it should be OK. I've been pushing 6 pounds through my 119k mile L98 for over 50k miles and no issues yet. I could probably push even more boost since the L98 has a lower compression ratio, but I dont want to chance blowing it up since its my only working car at the moment.

 

That is crazy, I have been reading more and more of this about the LT1's. Do they really have such a lightweight block as to distort the bottom end simply by putting another set of heads on it? Or even replacing headgaskets on the heads you already have?

 

Check out the specs here, but keep in mind they are using the stock LT4 cam (not the hot kit). I'm not sure if this documents all the differences, but you can see they run different crankshafts and the torsional damper is different (and of course the top end is different).

I say do it. but 6 psi MAX (effective 15+ cr)

 

Mine (L98) held together, while I had the turbos on it (bought it at 50k, turboed at 75k, pulled the engine at 100k). Everything still looked decent... Key is limit boost, and never ever detonate. I ran rich, and conservative timing...

Andris

 

I’ve only heard of that one place, in the last GMHTP. I’ve never heard of that actually happening to anyone. Has anyone out there actually seen it happen?

Considering how bad GMHTP’s tech has gotten this year, I wouldn’t be at all shocked if it turned out to be a crock of ****.

 

I heard it there as well but not only there, they were quoting some of the sponsored shops and Im sure those shops feel you should leave that kind of modification up to "professionals" like themselves lol

 

Crazy, it's a converted LT1.

Since you guys are familiar with GMHTP, you should have heard of a company called MOrgan Motorsports out of CA. They usually do 1-2 build-ups of some kind in each mag.

They built this car, and didn't take any shortcuts.

I have over 15k in receipts from the previous over for the modifications.

The heads flow over 290 cfm on the intake ( that's just plain ridiculous) The cam is a Comp grind but it's custom and I'm not sure of the specs but the car has to idle at about 950 rpm so that there is proper vacuum, and it STILL sounds so lopey you wonder if it's even supposed to be run on the street.

An AFR Hydra-Rev kit was also put on the car to control valve float since the car makes peak power at about 6450 rpm. It doesn't miss a beat.

I changed the plugs the other day and they looked freakin' awesome, especially since they had 40k miles on em'! no oil, or crud, so the bottom end of the engine seems to be in good condition.

I think I'm gonna buy a Vortech for it soon. I can't wait...but I just hope I don't break anything!

 

It's a load of crap until I hear someone like David Vizard say it's fact.

GMHTP tech frankly stinks.. and now that the former editor moves to PHR I expect the same downward spiral there too.

It all comes down to whatever the ad sponsers want printed. Might as well look somewheres else to get honest and accurate information. It's all about $$$.

 

Most of my tech reading I get from Racecar Engineering and Race Tech, both british mags. Circle Track sometimes has some decent cutting edge articles as well, but everything I see in CHP, PHR, GMHTP, HotRod, etc is pretty much the same old stuff with different pictures... The last good tech in the mainstream mags was from Ray Bohacz, but he's doing 5.0 stuff now...

A.

 

heh, I don’t know… the last few things that I’ve seen written by him sounded like advertisements also. Was it in hotrod or someplace that he wrote an article on tech tips to get those last few hp out of an engine and every single one was use x brand _____ and you’ll get… Though I still haven’t thrown in the towel with him…

Bohanz sold out a while ago. At least as far back as the Evans cooling thing in gmhtp(for those of you that don’t know, he’s got a stake in the company and started doing tech articals on their coolant and advising everyone that had a cooling question to go with it). But he did write some other reasonably good tech. I would put that as probably the last time that GMHTP had a decent tech editor.

WRT to the LT1/spun bearings thing, I wrote this on some other board or list, but look at it this way. They basically said that if you’re going to do it, you should get the engine rebuilt at the same time to prevent spinning the bearings. Now someone tell me how you’re going to tighten the heads after an engine rebuild in a way that will not put the same stress (and distortion) on the block then if you did it before a rebuild?

 

Now we're getting somewhere! There will now be different line honing procedures if the user is running studs, which are just tension in the block, or bolts, which might have some torsion as well as tension. It'll probably end up in the articles as: You must run ARP stud part #xxxx, while using lube ####, with the engine block at 74.5 degrees, between 60 and 65 relative humidity, have the block align honed using Sunnen Honing Machine ####, with brand new diamond stones, brand new oil, while consuming electricity only produced by utilizing the change in potential energy of dihydrongen monoxide. Heh. Just slap it together, and run it!

 

you know, I don't think that it would be a bad idea to do things like line honing with the heads bolted and torqued in place, but will it really make a difference? probably not.

 

1990 Iroc with a R-Trim vortech and 15psi, 103k miles on the car still runs hard, but i did did a lot of dfi tunning to get it to run.

 

Why don't you call Morgan Motorsports if they built the motor? I read one of their articles about a N/A LT1 383 buildup and the compression ratio was over 11:1. Maybe they'd have a record of what was done to your motor and would be able to give you some advice on the blower.

 

I already contacted them and they don't remember crap, really pissed me off. They builut this car almost 3 1/2 yrs. ago when they were first starting out.

Now they act like thier poop doesn't stink.

I wanted them to re-tune the DFI and they said it's pretty much obsolete and they don't really use it anymore.

The compression ratio should be what ever the LT4's are stcok.

The bottom end has around 85k miles on it.

 

I would listen to what the big dogs here say and keep the boost conservative and see what happens. Good luck

 

"paging saturn5"

 

since u guys touched on the subject of magazines.I just like to say that all of it is (carcraft,hotrod ,theyare the same mags to by the way)
all there engine build up are
there track times are
they juice all the numbers to sell their sponsors products.thats how they make money.one year its all edelbrock this and that and now its all afr.whats next 1000 hp 302 for 4000 bucks
dave

ps i let all my subscriptions run out

 

I had a basically stock 350 TPI Bottom end, put 11psi to it, didnt lower timing or add fuel pressure lasted 3 blocks
oh well now I have a 383 with 8.5:1 compression
much better!