408 motor build for blower

[badbluedak]

hey whats up guys I was wondering what suggestions you would have on my motor build I currently have a T-trim bolted on that I have ran on the truck for a few years the motor is getting tired now and has some blow-by issues I have a block machined for a 408 and main studs now I'm trying to figure out if I should build A lower compression motor and add more boost ? or If I should build like A 10:1 and run boost ? I would like to take advantage of the T-trim and run as much as possible but I know that 10:1 is going to limit me.SUGGESTIONS

[Intense RT]

I'd build it with around 10:1 and make it have power NA. For a cam, 112 - 114LSA and at least 230's @.050 duration. This will keep power when boost is low and the wider lsa will tolerate more cyl pressure without detonation.

[danbap]

10:1 seems a little high

[Intense RT]

10:1 seems a little high I know it's unconventional, but with a centrufugal, I'd probably go this route. It's no different than a sc on one of the new Vettes. Just have to run less boost but it'll still have strong response down low.

[danbap]

on mine i was going to go 9.5 for the same reason but every one i talked to said thats to high. 9:1 or 9.25:1 is where im going to build my 408.

[dakotapimpc]

mine is probably around 8:1 and has tons of power down low

[mtlcafan79]

You tuned yet?

[dakotapimpc]

i just have a box tune from when i bought the sct its running really rich still i drove it around my point yesterday seemed like it had some good power didnt really get into it just bumped the throttle deff has the torque i found that out befor i switched the fuel system and added the blower

still have a small oil leak somewere and need exhaust its going to go for exhaust sometime next week so soon your more then welcome to swing by if u want and check it out

[Intense RT]

Running more compression than what they used to recommend back in the day is the "latest" thing nowadays and seems to work well with good intercooling, Snow kit, or both. I'd at least be in the 9:0 range or a little higher.jmo

[danbap]

thats what im going to do it be right aroud 9:1 and i have smc meth injection so hopfully that will work out good.

[mtlcafan79]

@pimp

Who's doing the exhaust? MBS?

[bad360rt]

Unless you're planning on 20+psi, I'd keep it around 9-9.5:1. Ken is running 10's with 9.5:1 cr and 8psi.

[Lederip]

I run 9.5:1 on my Vortech 409 with around 8# of boost.

Also inject Methanol and run an Intercooler.

[danbap]

Unless you're planning on 20+psi, I'd keep it around 9-9.5:1. Ken is running 10's with 9.5:1 cr and 8psi.

is he running methonal?

Lederip

could we have more specs on your engine and 1/4 mile/dyno?

[Lederip]

i
Lederip

could we have more specs on your engine and 1/4 mile/dyno?

I ran the engine for over 2 years with NO intercooler or alcohol injection. The BigStuff3 helps in controlling fuel (pump gas) and timing at 14:1 dynamic compression. I also relive some boost with my cam profile

Its a Stock Block bored 35 over with splayed 4 bolt mains, Callies 4" Crank, Eagle H Rods and custom Diamond Pistons. KRC ported R/T heads. S-Trim, F&B 58mm, Bell Water to Air intercooler and Methanol injection.

It Runs 10.6xx @ ~ 12X mph
race weight ~4000#
Pre intercooler it made 525hp.
Its making around 600hp at the wheels now

[danbap]

I ran the engine for over 2 years with NO intercooler or alcohol injection. The BigStuff3 helps in controlling fuel (pump gas) and timing at 14:1 dynamic compression. I also relive some boost with my cam profile

Its a Stock Block bored 35 over with splayed 4 bolt mains, Callies 4" Crank, Eagle H Rods and custom Diamond Pistons. KRC ported R/T heads. S-Trim, F&B 58mm, Bell Water to Air intercooler and Methanol injection.

It Runs 10.6xx @ ~ 12X mph
race weight ~4000#
Pre intercooler it made 525hp.
Its making around 600hp at the wheels now

thats pretty nice set up. was the 525 at the wheels with meth or was that no intercooler and no meth?

[Rtspeeddemon]

I run 8.5:1 on my Turboed 408 with 13# of boost.

Also inject Methanol and run an Air-to-Air Intercooler.

Also add 5 gallons of C16 race fuel at the track to insure no detonation.

[Rtspeeddemon]

I run 9.5:1 on my Vortech 409 with around 8# of boost.

Also inject Methanol and run an Intercooler.

Hey Ken have you run at all this year? ... haven't heard any results from you.

I have been pre-occupied this year and have had mine to the track only twice, will not likely run again till fall as I have a lot of personal things going on this summer.

[Lederip]

thats pretty nice set up. was the 525 at the wheels with meth or was that no intercooler and no meth?

Sprayed Methanol 50/50 during the Dyno runs.

It made a huge HP gain when I added the intercooler, mainly from the ability to add timing and trim the fuel.

Also found that the truck liked the 100% alcohol and a rich A/F (10.5:1) when spraying. I run an A/F of 11.2 with no Menthol spray.

[Lederip]

Hey Ken have you run at all this year? ... haven't heard any results from you.

I have been pre-occupied this year and have had mine to the track only twice, will not likely run again till fall as I have a lot of personal things going on this summer.

Kevin, Glad to see your still around. Haven't been to the track racing this year. Trucks running great and mainly used as a street machine. Nobody seems to want to go to the track anymore:angrywife:. I'm retired now:rockwoot::rockwoot::rockwoot:

[Rtspeeddemon]

Kevin, Glad to see your still around. Haven't been to the track racing this year. Trucks running great and mainly used as a street machine. Nobody seems to want to go to the track anymore:angrywife:. I'm retired now:rockwoot::rockwoot::rockwoot:

Retirement good for you Ken I know you had talked about that coming up!

We still need to get our beasts running off against each other someday.
Two 10 sec runs side by side would be a 1st i think for the club.

[Intense RT]

That would be cool to see. Here we have all these 10 second trucks now,...and everyone is staying home pretty much. Not much talk about the drags. Losing interest?

[danbap]

i guess the other thing is if i run lower boost you could rise the compression ratio up too. to get the desired hp.

[Sick 660r]

Im around 9:3 with aluminum heads and boost will probably be around 14psi.

[danbap]

i dont have the money for eddys though.

[danbap]

after talking to more people and research im thinking of going a little higher then most around 10:1 and say 10-12psi.

[Rtspeeddemon]

after talking to more people and research im thinking of going a little higher then most around 10:1 and say 10-12psi.

You really need to have a pro research this. 10:1 is huge on a boosted application and your cam profile will determine where your static compression ratio ends up as you add in boost. You could end up 16+ in compression and things are going to go boom unless you have some pretty stout fuel controlling detonation.

[mtlcafan79]

Turbo Ed brought up dynamic compression numbers and octane requirements on Delphi once. It was pretty eye opening to see what was required.

[danbap]

do you have link to that sounds like a good read.

[mtlcafan79]

I'd have to look when I get home. Google dynamic compression ratio calculator and you will come up with a lot of stuff. You will need cam timing specs and basic engine specs to use them. A lot of it goes way over my head even.

[Intense RT]

Go to Speedtalk forum, register, and ask engine builders, tuning gurus. Lots of intelligent conversation over there. Just ask the question like "What is the highest static compression advised" Then go on to to explain in the post what your plans and specs of the engine are.

[2k1AmberR/T]

Here's one that I've read recently that was posted...what Ed posted on Delphi was pretty ridiculous with the cylinder pressures and the weather conditions and everything. It seemed like something he just typed out himself though, nothing you could 'google' I don't think. You'd probably have to have a paid Delphi membership to go back that far and re-read what he said.

http://members.uia.net/pkelley2/DynamicCR.html

[danbap]

thats a good link i cant get the program to work, only thing that one lacks is boost.

[dakfink]

It's all going to be in what Tuning and Fuel you want to run.

Several years back we put a cobra (4.6l DOHC) together and ran 9.5:1 with 15psi boost and no-intercooler.

With 100-octane available in Kuwait at the pump and of course Kuwait's hot-ass summer evenings we tuned it for a final 708 rwhp.

We did back it down for Premium Pump gas and we got 635 rwhp with 12psi boost.

Your base compression ratio is only going to limit how much boost you need to make to get to your goal.

With SCT Tuning available and the Issue of Belt Slip with Superchargers on these engines. Running a higher base compression is actually the way I wish I could have gone years ago.

I used to run at 8.3:1 compression and with out the S/C in boost it was a PIGG!!

I would look at 9.5:1 and 8-12psi Boost with a good tune and premium gas all the time.

10:1 is do-able BUT your probably going to be limited to about 5-8psi boost on premium pump gas.

A good intercooler will be very beneficial as well. Preferably air-to-water