Ti Springs / Retainers

[North Coast Cab]

What is the RPM or HP point at which stronger springs or retainers are required?

[Quicksilver]

It is all about RPMs. On the 3.2 you are about at the limit at 6500-6800 (the Motronic's rev limit). With better springs the valve train will spin a fair bit higher.

But you have a different problem in the 3.2l motor. The rod bolts are a "stretch to torque" type and they won't take any higher revs. I like to call them rev limiting rod bolts.

If you over rev they may not blow at that time but it increases the stretch in the bolt and decreases the preload. This makes the engine fail a bearing at a later time. (sometimes months later!)

If you want to really spin the motor you will need to put in ARP or Raceware bolts. This will increase the rods safe speed by at least 1000 rpm.

There are a couple other things you will need to look at. At the minimum you will want to put in the later cam oiling restrictors to keep the rod bearings safe. A better idea is to use the 964 oil pump (and the cam oiling restrictors).

The kicker is that unless you change the cam and do some intake work it isn't going to make any more power when you spin it faster so you would want at least the 964 cams and some sort of upgrade in flow for the intake. Carbs would be a good choice.

Getting more expensive isn't it!

[randywebb]

I'd put in the TI retainers always.
Next, ARP rod bolts

The springs are quite good already, JW makes better ones...

[North Coast Cab]

ARP Rod Bolts
DC-20 Cam
Oil Line Restrictors
964 Oil pump

[Jeff Alton]

Before you spend the money on springs, ask John (the guy doing your cams) if he thinks they are required with that cam.

Cheers

[drsimonwong]

I'm doing that motor with DC20's. John recommends his performance springs with stock retainers.
Simon

[ChrisBennet]

On a stockish 3.2 the springs are for safety not performance. Spinning the motor faster isn't going to get you (much) more horsepower but better rod bolts and stiffer springs (esp with a longer duration cam like a the common 964 grind) might make the difference between going home on a trailer and saying "oops" next time you miss a shift.
-Chris

[Steve@Rennsport]

Originally posted by Quicksilver
It is all about RPMs. On the 3.2 you are about at the limit at 6500-6800 (the Motronic's rev limit). With better springs the valve train will spin a fair bit higher.

If you want to really spin the motor you will need to put in ARP or Raceware bolts. This will increase the rods safe speed by at least 1000 rpm.

Camshafts limit the real RPM range in any engine,..the mechanical bits are simply along for the ride,...

3.2's use the factory sintered-metal retainers and these can break when the valves float. As valve springs age, they lose some tension and the threshold of valve float slips lower. A "gentle" missed shift or repeated banging into the rev limiter can cause valve float and a broken retainer and this can get VERY expensive.

Installing ARP or Raceware rod bolts will cartainly NOT raise the rods "safe speed" by 1000 RPM. If one is going to run these engines past 7100 RPM, you need either Pauter or Carrillo rods. This is a very complex subject as there are many oiling issues to deal with at higher RPM.