Compression and turbo lag.

[Black 03 Mach]

My original plan is buy an aluminator from american muscle with the 8.5-1 compression and a 76mm turbo. That was all gravy until i got to thinking deeper about turbo lag. Im going to be driving the car fairly often, on the street. I really don't want to resent starting to move from a red light. American Muscle does offer a 10-1 compression as well. Most of my driving will be done at around 5xx whp for the most part and 650ish when it is needed. Lastly, should i switch it to twin turbos instead of the big single to help the spool time if I were to decide to get the 8.5-1 longblock?

Thanks in advance.

 

[corysmach1]

10:1 comp. E85. T76....smash some vettes.

 

[86merc]

You are looking at only two things of a complete combo. Lots more to know before someone could really make good recommendations.

Compression will help off boost performance more than helping spooling. Which in a street car it is nice to have some extra grunt when not in boost. I would bet you would get more help with spooling by choosing a turbo with the correct turbine wheel and housing than the bump in compression. But again, you have to look at the whole combo to perform like you want it to.

 

[itSSlow98]

Intake setup, exhaust setup, turbo specs have more to do with spool then compression. I am running a built bottom end at 8.5:1 compression and a turbonetics t76 and im at full spool by 4250rpm. 3" dowpipe and 4" intake. I have no problems down low but its definetly no monster down low. Once you hit boost its all over though.

Keep in mind the t76 is somewhat old school compared to new precision billet wheel/dual BB turbos that will greatly help with spooling.

 

[Black 03 Mach]

Id love to do e85 but i never see pumps that carry it and id rather not get caught with my pants down. I was playing with the idea of piecing a turbo kit together, but will most likely go with hellion because i want the car ready for carlisle. Lethal performance offers:
"standard" 61mm
76mm precision HPS BB
76mm precision hps
Precision 67mm billet wheel
Turbonetics 61mm billet wheel

Only need 650 hp out of it so i dont want to buy something im not going to use to its full ability

 

[86merc]

But anyone with a turbo car knows it is only a matter of time before the boost controller gets turned up. haha

And remember the compressor and turbine do effect each other to some extent. But in a street application the turbine side will be what will help the spool more than any thing. But a turbine side that is small to spool quick may have back pressure issues when you try to turn the boost up.

I know a lot of guys that use that billet 67mm in the 76 compressor housing. They are making 650ish rwhp on moderate boost and pump gas. Call a someone that specializes in turbos, give them your engine specs, goals, etc. and they will get you the right turbo for your application.

And I am in the same spot as you with E85. Not many stations carry it around here otherwise I would be on it too.

 

[AluminatorSnake]

Find a different motor...and yes i have the aluminator 10.25:1 to make the claim.

 

[Black*Death]

Why are buying a motor and not simply having yours rebuilt?

 

[Black 03 Mach]

Because its 46xx for dissassembly and clean up. Add cost for forged pistons/rods/hardware, shipping there and back and it will come real close. Plus the extra time to get that all taken care of just does not seem worth it to me.

 

[AluminatorSnake]

Because its 46xx for dissassembly and clean up. Add cost for forged pistons/rods/hardware, shipping there and back and it will come real close. Plus the extra time to get that all taken care of just does not seem worth it to me.

There are lots of things to think about. I felt the same way as you did and pulled the trigger on the Aluminator. Now i fully regret it. My aluminator is pretty much new but after my procharger install at only 10# i have tons of blow by and oil running into a catch can. The motor is great to stay N/A i just dont think the rings are the proper ones for boosted applications. Also there is a reason that when I was at fastlane getting my car tuned that the owner and manager will not let them order these motors for customers. Too much nightmare and too many failures. Im already saving up for my new block. Please dont regret it and build your own block.

*Also since the 10.25:1cr aluminator is for N/A and youre gonna put a turbo on it, the warranty youre paying for and think looks good will be no longer.

 

[Black 03 Mach]

How long does it typically take to dissassamble, clean and reassemble? My goal is to have the car ready for carlisle ford nationals

 

[01yellercobra]

Depends on how much work the machine shop has in front of your motor and how much machining is needed. Plus waiting on the parts after they're ordered.

 

[rocket5979]

While there are many other factors that have to be correctly taken into account for a properly running turbocharged car, I always stay with higher CR with a turbocharged street car so it is not gutless off the line or just before I hit boost while on the street. I prefer to stay in the 10.0 - 10.5cr for turbo street cars. Strip only cars I drop the compression about a point because you are racing under different conditions that don't really require off-boost performance. My current turbo car is the Pontiac G8 GT in my sig with twin Garrett BB turbos on a built 402ci stroker motor at 10.1:1cr and running a 3k stall TC in the trans. I usually don't have any problems with waiting for delivery of power or torque. ;-)

 

[ruthless]

"Only need 650 hp out of it so i dont want to buy something im not going to use to its full ability"

If thats your power goal I would save cash and go with a twin screw.

I dont have much lag at all with my setup but it took more than what a Hellion kit cost to get to my goals for on the factory stock engine.