im new to muscle cars coming from the import world i wanted to build a atleast 500 hp straight six i was wondering built what is the limitations of this motor and im wondering what rpms would it spool a say gt35r i noticed most people arent running but 16psi for some reason but i really want to build something different than the run of the mill 350 with vortec heads and nitrous how much boost will the 250 hold with low compression forged pistons etc... is there a weak link i dont know about remember im used to pushing 25psi on a 4 cylinder just wondering is it possible with the six i want to build something to bully up on a mild built 350 and surprise the older guys with
how much we talkin im deployed so yea i can swing about anything i want i just wana know whats required ive already ordered the top hat for the carb im gonna run plan on using a demon just need to know how far i can take the motor built im thinkin of a borg warner sc300 for it its a 750-800hp turbo but if i cant push the turbo to a certain psi i want then theres no use in getting it i should get a more spool friendly turbo like a delta 42
Step 1: buy Santucci's book, and read it thoroughly.
where can i buy it at, this project is gonna be a slow project i plan on takin my time and doing it right the first time
Not available yet, I'll post a link.
Amazon.com says it will be out any day. You can pre-order it. I'm waiting for mine. A lot of people recommend Maximum Boost by Corky Bell. I bought that and found that most of the book is available on line through different articles written by the author. So if you want to save some money you can spend some time surfing the net. Leo's last book is available also.
Amazon evidently believes that the old version was printed on gold leaf - check the prices.
I'd try eBay for a used copy.
Bell's book is very interesting - he has rather strong opinions on many topics, including his own brilliance. However: very few actual recommendations. I'd join Inliner's to get Tom's work to get close to the basic needs.
What size Demon? Are you going to modify it yourself?
Commercial or fabricated exhaust?
I totally agree on Bells book. I hope Leo's new book has more on F.I and turbos.
For all practical purposes 300-400 hp is easy to get. 5-10 PSI will take care of that.
Mighty6 has a 292 putting down in excess of 700 HP. I believe at around 19 PSI. His is a very purpose built engine and will not be as streetable as a 400 HP engine.
Turbo 6 also has a nice turboed 292 that has to be around 600HP.
Take care over there and come back safe.
Tom
How many RPMs to get the GT 35 turbo to get into boost?
Around 3200-3400 w/a 250 CI W/a A/R on the hot side of .83 or so.
Less RPM needed w/a .63.
Most guys w/turbos in the US are using 292's. ,it seems.
But guys w/there 250's in Brazil turn anywhere from 6800-7500 + RPM.
Mighty6,says his truck would be streetable w/the turbo set-up more so w/the turbo than the nitrous set-up he had.
He said he would not want to drive it on the street for fear of getting into an accident.
Dougals in Brazil,made 700 hp @ the wheels w/12 psi.
He also ran as high as 36 PSI form the turbo.
IIRC he had a SC400 turbo T6 w/his race car.
MBHD
im not sure what size carb to go with im thinkin a 575 would do the trick with a electronic fuel pump, what is required to hit 500 do u need to have the block sleeved or will just a piston and rod combo do ive never used carbs im used to fuel injected vehicles with fuel controllers, i bought this car as a learning experience, and so far nothing has happened over here its just hot as hell everyday
I'd begin with modifying the head.
Once you either run out of casting or money, your porter will tell you how big an engine it will support.
The carb size comes from that, and a lot of the cam choice, especially the intake/exhaust split.
i was thinkin a port and polish and build for more rpms where i can stay in boost longer through each gear especially if i wana get a hugh turbo im not really worried about a fully reworked head because that would just up the compression and be less boost that i could run safely without meth or race gas
a fully reworked head because that would just up the compression
Why is that?
My philosophy is to buy the best cylinder head you can afford and build the rest of the engine around it.
My philosophy is to buy the best cylinder head you can afford and build the rest of the engine around it.
X2
MBHD
X3 - the head has to be done before you choose a cam, since not only the actual flow (CFM) but the intake/exhaust bias must be known. The flow results are what your cam guy wants to see.
A good head with everything else stock will run just fine as long as your quench distance is good.
This is one place where I normally tell my customers to spend money (don't do it yourself unless you have a few years of successful porting under your belt).
As an alternative to the 250/292 engine. Consider swapping in a 4200 inline 6 vortec out of a trail blazer - 290 HP stock. At 10 psi it'll be close to 485 HP crank. Its more work but in my opinion your starting with a much better engine with 4 valve/cylinder. A ported 06 up head flows 320 CFM in. and 230 ish exh.
Most likely the engine is stock form will take 10 PSI as long as you keep the tune safe AND do not rattle the engine. Keep the revs under 6300 and have some fun.
Good low mileage engines can be had for under $1100.
efi-diy
I think we all agree the 4.2 is a better engine.
That's not an issue.
If you are starting from scratch,dont have an engine,by all means,go w/the 4.2,it will make more power ,it will be different,pretty sure it's lighter than a 250?
I said it before,if I did not have all the parts for my 250,I would go that way also,,but I am stuck w/the 250 for the time being,but I like the old school engine & if I can run 9's in a street car ,all the better.
MBHD
Just offering options for folks to consider.
Y'know, I would almost think that efi-diy is biased.....
The 4200 is a serious contender when it comes to upgrading for performance purposes. Unfortunately there are fools such as myself that just gotta go with the old engine as a base.
Paul
Looks like our OP was looking for validation rather than advice.