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View Full Version : Whats the Weak Link in These Engines?

dug
05-21-2003, 07:23 PM
Anyone ever replace the pistons and rods and spin these motors past 8k rpms and live to tell about it?
Night Wolf
05-21-2003, 09:11 PM
The Quad4 is a DOHC engine, and in some sad cases, SOHC... either way it is still based on OHC design... no push rods

I am not too sure how far they can go, AFAIK there is not very much aftermarket if any for them. I think I heard one time someone got 250-300hp out of a stock internal Q4... although he was sprayin'
4kQuad
05-22-2003, 05:33 AM
week link is Head Gaskets, and Heads have a way of cracking.

The bottom end is quite strong on quads. As quads are computer driven motors, you will have to get another chip for the computer before you can break 6 someting grand.

There is not a lot of after market parts for quads.
graden
05-22-2003, 10:15 AM
HEADS HEADS HEADS...... went through 2 in 3 months. than mabey the lifters
DominionTuner
05-22-2003, 12:48 PM
I believe the highest RPM you will acheive is 7400 that is with a W41 Chip on an HO motor. The LO will not get that high, the LO usually gets fuel cut when you pass 6250 or hit 6250.
dug
05-22-2003, 01:25 PM
Yeah the rev limiter is gonna be tough to get around. How durable is the valvetrain? Is it a matter of changin the springs and youre good to go? Or do you need some heavy duty pushrods? ;)

Also, Ive been seein posts about heads cracking. How common is this and what is the cause?

tia:cool:
LargeFish
05-22-2003, 01:46 PM
No pushrods on OHC engines.
dug
05-22-2003, 02:00 PM
I was joking. Thats why I had the wink afterwards.:D
Fast_am
05-25-2003, 06:38 PM
Originally posted by dug
Yeah the rev limiter is gonna be tough to get around. How durable is the valvetrain? Is it a matter of changin the springs and youre good to go? Or do you need some heavy duty pushrods? ;)

Also, Ive been seein posts about heads cracking. How common is this and what is the cause?

tia:cool:


factory Valve train can handle 8000RPM. but there is no point going that high. the Cams wont make power past 7000RPM. W-41 cams will work with the factory springs. Comp cams makes a custom grind. for .430 lift and 222 duration. also there is W-41 Hot cams .411" lift 242 duration. these require after market valve springs. if you can track down fbod383 he can tell you how he made 217WHP on his stock compression Quad4.

W-41 chip can be from 7200-7400 RPM fbod383 has a custom burned chip for 7600RPM.

Click the link in my sig. and veiw our FAQ section. we have links for all aftermarket supliers.