I have the LT4 conversion and I won't say it isn't possible to get that kind of power out of it, but I haven't been able to. With my best et being a 12.7 @ 107

I do however thinkg it has a lot more potential to it, with more tuning, also I still have stock injectors, throttel body.

I also have the Chevy High Performance it was in. The article says that the in addition to the LT4 Conversion that it also adds a 52mm Throttle Body and full length headers and made 429hp @ 6100rpm.

 

True, but the MoTeC alone doesn't add power. It's the tuning advantage that it offers...

 

The LT4 was underrated from the factory. In proper tune (Vette ECM) the LT4 will ususally put down 300RWHP. To give you an idea of how big a difference tuning can make, the LT4s that went in the f-bodies using the stock LT1 tune and fuel injectors typically dyno right at 280RWHP, but jump right back to 300 with a good tune. I'm not saying every LT4 conversion will hit 425HP (flywheel), but it's definitely possible with a 52mm TB, headers and a good tune. However, if I was doing a cam/heads on an LT1 f-body I would go ported heads and a bigger cam. You'll make better power and probably spend less. For me, a hotcam would be good because I only need the cam.

 

One of the best systems out there.

 

are those ported LT4 heads?

f383, if you got a scanner, could you scan that article? 800x600 would be fine
i'll put it up on a website for everyone if you send it to me

 

The heads on my car aren't ported, nor are the ones used for the CHP article.

I just put the CHP article about the LT4 Conversion on my webshots page. Under CHP Article

http://community.webshots.com/user/bobbyakers

or the link in my sig.

 

Eeek REALLY hard to read!
Cool pictures though

 

thanks formula383, i sent you a pm

 

Here's the original site for the conversion package:
http://www.moreperformanceinc.com/383lt1.htm
and here's their link to the article:
http://www.moreperformanceinc.com/lt4artic.htm
They dynoed it on an engine dynoed with long tube headers and a 52mm throttle body, and it looks like it didn't have any cats or mufflers after the headers, so that plays a role too.
Peak numbers with the LT4 heads, LTs, and 52mm TB were 361HP@5,500 and 378lb-ft@4,600.
Once they added the Hotcam they hit 429HP@6,100 and 400lb-ft@5,300.
With a 15% driveline loss that would come down to 365RWHP, which I think is very doable. If you are running cats & catback, though, you should probably expect to loose another 5-15RWHP, so you would then be looking at around 350RWHP for an M6 car with cats and full exhaust.

 

The LT4 is definatley over rated, Horse power wise, however the kit will give you a great amount of mid-top end power. The LT1 lacks mid-top end power but has awesome low end power!

 

Thanks LT4Firehawk I knew I downloaded those pics from a site a while back. Just forgot which one. That is where my pics came from.

I still think there is good power that can be had from the package, but I am thinking about keeping the stock LT4 heads, and intake and going with a bigger cam though.