doubler

Thanks Ed, I hope to learn more tommorrow when I make some phone calls. You have to admit though there is "plethora" of choices out there confusing us guys that have not built an engine this big. It would be much easier to build a 565 and go with the Dart 355's as they seem to work good and a lot of engine builders seem to use.

Anyways, I will start big and then be talked down... :lol:

cboggs

I can offer some experience with the head issue, ..

First, .. if it's a limited street, .. just go ahead and put some
compression in it, .. 15:1, .. you're giving up too much to use
a fuel that doesn't belong in a $20K engine.

a GOOD 24* conventional style head will make well over 1000 hp
on an engine this size with a race style build, ..
but a good spread port will be better.

We build an Edelbrock 24* with a 2.4" intake valve that does this, ..
http://www.racingjunk.com/post/92317...ictor-CnC.html
but a Good Brodix 1803 with a CnC port will make around 70 more, ..

and if you go to a well ported Dart 11* and 15.1 comp you'll be able
to make 1250 - 1300, ..

As far as chamber and valve angles, like the Dart 18*.
the primary performance gain is in the chamber and flame travel, ..
smaller dome etc. In a 11:1 engine I don't think you'll see much
difference between Dart's 24* and 18* heads because you're not taking
advantage of the better head.

Now with conventional 24* VS a spread / raised port style head
like a 14* Dart big chief you will see a difference because of
the more efficient port design and port velocity profiles, ..

Curtis

doubler

Thanks curtis, yes it is limited street and I have been mulling over the compression as it doesn't see much street use. Just drive it to a car show and some short cruises. So, its not like I am filling up with race gas every week. Some day I would like to get it into Hot August Nights...that would be a blast.

The reason I was thinking of going large was that was the only way I can make the hp I want with lower compression. It takes about 900-950 to get a 3500lb car in the low 9's. Mine weighs 3200. It will take 1100+ to get in the 8.50 heads up class. I wanted to try and get has close as I could so I don't have to run a lot of nitrous. 250 shot or less...I was planning on running 100LL playing on the street and race gas on race day. I might be able to go a little higher cr with the 100LL or I could mix some race gas with it. Anyways, it would be a lot easier if I would just move up in compression.

On Shaffiorfs 632's there is a 100hp difference between the conventional and 18* head at 10.75...just throwing that out.

cboggs

I wouldn't pay too much attention to advertisments, ..

you have goals that are at each end of the chain, .. street and heads up ?

Curtis

doubler

I have a friend that has a RM 555 in his camaro runs low 9's. He drives it on the street once in awhile. I wouldn't call it a street car either, but would like to do something close to that. They aren't driven very many miles on the street. At those power levels, can't be very streetable. Anyways, those were some goals I was thinking the car could fit into that class someday, since I want to upgrade my 502 700hp pump gas motor which is not all that streetable either. Maybe my goals are not realistic...Car has run a 9.23, so didn't think what I am trying to do is to far out.

I can see why people do buy the GM572 now though. Too many decisions to make. Just buy it and install it and be done with it. I still don't feel you are getting much motor for your money though and not much hp. There was a post over at speed talk about pump gas motors and one said they got 850hp from a 572/10.2 motor. Sounds a little high for that cr...

I have my Dart 345 pro1 heads (fresh), but don't think they would work that good on a big motor?

dak697

if you are in the Northwest of the country have you tried PED or Davidson Racing Engines .. Both builders have a good name in the NW for race car stuff. There is also Madcap which I've seen have pretty good results on their top dragster/sportsman stuff. Dean