forced induction suggestion and values

[yellow1098Greg]

Well i have a carbureted pontiac 400 in my 77 trans am and my compression is alittle low so i was thinking about doing something abou it to get my power where i wanted it. I bought the car Aluminum eddy heads but they are the lower compression 87cc ones. So i was thinking about getting the heads sold and switched to fix my low compression and get more power....

But then i thought why would edlebrock sell lower compression aluminum heads for the same price as the higher compression ones? My light bulb answer was forced induction!!! Must be for those kind of applications.

So my question was before i decide to sell them and get some more high compression heads, first would it be wayyyy more expensive to do some sort of forced induction and which would be best bang for buck? As well as i know and agree with not going all the way usually cost more in the end anyway, but as of right i just cant spend 6 g's plus. So i thought id get some ideas from you guys, or if you know anyone that wants to sell a supercharger for a good deal lemme know. (because the more power the better ) thanks

[opnwide]

its def more expensive to do forced induction, but worth it IMHO. A 455 crank will give you a nice hike in compression and cubic inches.

[yellow1098Greg]

i looked at your threads there and i love the twin turbo 455 setup. What kinda numbers is that setup giving u?

[opnwide]

Haven't got any numbers yet. I figure around 450-500hp conservatively NA. Add 10lbs boost and 750-800hp is pretty reasonable. Its scary. I know one time I hooked up my vac lines wrong and maxed out my GT3040s at 16psi. They're rated for 500hp each. 16psi on top of 450-500hp is at least 1000hp so I guess the rating is fairly accurate. After changing my shorts, I fixed my little mistake and put the hoses back in the right place.

[MonzaRacer]

Big issue on Pontiac block though is that over 600 hp your liable to split the bock down the middle. Build a Pontiac for torque, figure one or two of the ebay GT45s and have the guy over on theturboforums.com build you a "crutch" holley and run it blow through and shoot for about 500lb ft of torque

[MonzaRacer]

OK so me , now with more time to explain some things, get more into detail. An Edelbrock head, if according to my information on flat top piston engine SHOULD have around 8.4 to 8.8 to one. According to my information you can remove 0.005 of chamber to decrease the volume by 1cc and according to my information 71cc on flat top engine is 10.2 to one, on a dish piston engine would be around 9.7 to one,,,,both eminently ideal for a simple blow through turbo set up.
Biggest issue the Pontiac has is Arma-Cast rods, will fine for low rpm torque production with limited abuse.
Now if oyu were to pull it apart, slide in a good set of rods and pistons, good forged ones. A cheap set of h-beams and some stock forged replacement pistons, a small cam in the range of Comps 268H maybe a 270H is all you would need for a boosted set up.
Over on www.theturboforums.com one guy does whats a called a "crutch" modification on the power valve circuit of a Holley, this allows outside actuation of the power valve enrichment, which you could control based on exhaust air/fuel ratio rather than controlling it by vacuum which the car wouldnt have under boost.
Now rather than get ride of a superior flowing set of heads, as they were developed based on Ram Air IV heads, simply take them in and have them milled say 0.030" to 0.060".
An 0.030" should bring them to reasonable number with flat tops BUT consult Edelbrock first on actual compression numbers as I dont think with flat tops(need to pull my Pontiac info out of storage) you would actually need too.
Now remember one thing , Pontiacs are torque engines, no need to throw away a good 400 for a 455, simply have a 455 crank turned down on mains to fit 400 block but the 455 has issues in certain ratios of size. Actually for best of both worlds the 400 is near perfect when properly built.
Here is a link,,,READ THIS FIRST: http://www.wallaceracing.com/enginetheory.htm
The information came from HO Racings Pontiac power book, GET A COPY IT HAS GREAT INFO. Mine got stolen.
Good rods and pistons, you already have excellent heads and instead of using a screamer cam set up look towards using Pontiacs near perfect torque production (since you have the good heads) to build a solid engine base, if you wan you could turbo with a moderatly sized turbo and make way more than a stock 400 pontiac or even 428/455 block could take. About 600 hp is limit then longevity becomes issue.
You can look up reinforcing the stock block but if your going to drive it on street plan for about 500hp 500lb ft of torque and buy stock in your favorite tire company.
As for forced induction, as is , if you keep it under 10psi boost, be very conservative on tune and put a well tuned water/methanol injection on you could have LOTS of fun. For water injection look here on how to build your own set up: http://www.turbomirage.com/water.html
Several of my friends have done it and used several different adaptations of same susyem and for much less than other "professional" systems.
If you want economical fuel injection look at Megasquirt systems. you can build it your self, tune it your self and YOU become the professional.
http://www.megasquirt.info/
http://www.bgsoflex.com/megasquirt.html
http://www.megamanual.com/index.html
Where to buy:
http://www.diyautotune.com/

good luck and I have a set of closed chamber HO Pontiac heads Ill trade for those Edelbrocks but if you have flat top pistons your talking 10.5 to 10.75 to 1. Oh and I have access to a machine shop and can fully refurbish them too.

Oh yeah with closed chambers do NOT try and run real short duration cams, car will rattle its head off above 3000-3500. Ihave a 256 duration Iused with 10.5 to 1 heads,, not good, torque monster but NO rpm ability.