bkidston

I want to modify my 375 hp engine to 405 hp are the changes to heads etc
available, shape etc as to enable me to machine to the 405 hp spec. rings etc
I will buy any info would be appreciated.

Jeffvette

You're going to spend all of that money on labor and very little work for 30hp?

I've got a set of Dunn heads I'm willing to sell :rofl:


Seriously, you are better off having the the injector housings and plenum ported. This will pick you up an extra 15 rwhp. Which will get you close. If you are really daring, do the heads at the same time, andjust time your camshafts to the optimum setting. Don't forget to do a set of headers as well to finish off the package and get some real gains.



[Modified by Jeffvette, 3:46 PM 3/10/2004]

kabnvtt

[QUOTE]You're going to spend all of that money on labor and very little work for 30hp?
If you are really daring, do the heads at the same time

Not to hijack the thread but can you do some intake port matching while the heads are on the car? I am buying a ported plenum and injector housings from MrCrowley and will have them exposed. Or is it to risky?
(I've got a set of Dunn heads I'm willing to sell)LOL. :cheers:

Jeffvette

It is able to be done. You just need to get a dental dam or something to plug up the ports so you can vacuum them out. It's been done before, but not something I would really persue.

locobob

A good part of the 405hp cars extra 30hp is actually in the injector housings. The castings were changed resulting in a dramatic reduction in size of the primary injector bosses. This probably accounts for at least 10 of the 30hp and can be done with porting of the injector housing. The exhaust manifolds are supposed to be better on the late cars also but given the cost it would be more benefitial to buy headers than to upgrade to the later style manifolds. In short you are going to spend more money and get less power trying to duplicate the 405hp cars than if you simply do some of the tried and proven performance modifications.

Port matching heads on car? It can and has been done but it requires some very careful preperation and extreme caution. Definetly not a job for the faint of heart.

kabnvtt

Thanks Jeff And BoB for the advice, I think I will pass on doing it myself. As far as retiming the cams, with the right tools is that possible to do fairly easy once the cam covers are off. Thanks. :cheers:

The Lurker

BBBBBBbbbbbbbwwwwwwwaaaaaaaaa haaaaaaa haaaaaaa haaaaaaaaaaa.........

Now that is funny.

DDSLT5

Yeah - Julio may disagree too - bent 24 of the 32 valves trying to time the damn cams - not as easy as it may seem!! :seeya

Jeffvette

I think we just heard from the voice of reason. :hat

FU

You can easily do the plenum and injector housing pull. Then send them out to be ported up. Put on a set of headers and exhaust. Go out and have fun with all the new found power.

kabnvtt

Yep that pretty much answers my question, Is there much of a gain having the cams retimed? And being in Northern Ca. are there any mechanics that are well known to do something like that. Sorry for all the questions and I hope it is helping to answer the original question for the thread starter. :D

Jeffvette

Jim Van Dorn is, he's in Palm Desert. And yes there can be gains or losses had in timing.

The Lurker

On a stock motor there is only 15 hp at the flywheel to be had. After 10 hp you begin to loose lower end torque. There is much more cost effective hp for a motor that hasn't been opened up.

zr11990broken

Ok Lurk lets play pretend. If you wanted to go the other direction and get more low end tq how far could you go

The Lurker

So far it seems restricting the outflow of gasses and richenup the mixture does it. HP is down but torque is up. I don't know why for sure it seemed to work out this way. I was amazed when I saw it on the dyno.