Getting more 7M revs...

[CajunKenny]

Greetings all,

Soon I will be in the world of a Standalone and one of the things I hope to get is more revs. I'd like to see another thousand.

Here are applicable mods:
-Extrude Honed Intake Manifold
-Fidanza FW
-JT62 Turbo
-3.75" Elbow w/3" Exhaust the rest of the way
-Fresh Bottom End w/Clevite Bearings. Well Clevite Boxed Bearings anyway...

One of my concerns is whether or not the Crank Pulley will hold up. I have my sights on an ATI.

So, what does it take to safely get to 7500 rpm's? Put another way, what is the max recommended rev limit of a stock-ish 7M?

I'm hoping for first hand experience instead of hearsay. If you know what I mean...

 

[IJ.]

Valve springs will be the major fail point.
(1st hand experience)

 

[IBoughtASupra]

Well, it is pretty common knowledge that you will need upgraded springs and retainers to rev that high. The 7M crank would be better suited due to it being counterbalanced and has a higher stock RPM.

Fresh bottom end? I know you have a million of these Kenny, which one? Stock or the cheap motor that had aftermarket rods and pistons in it. With either one, ARP hardware will be needed.

Do I have a experience with this? No, but just the basics for any motor.

I do remember Ian saying a counter balanced 6M crank is better than a 7M one. Don't quote me on that until he verifies it though.

 

[IJ.]

Well, it is pretty common knowledge that you will need upgraded springs and retainers to rev that high. The 7M crank would be better suited due to it being counterbalanced and has a higher stock RPM.

Fresh bottom end? I know you have a million of these Kenny, which one? Stock or the cheap motor that had aftermarket rods and pistons in it. With either one, ARP hardware will be needed.

Do I have a experience with this? No, but just the basics for any motor.

I do remember Ian saying a counter balanced 6M crank is better than a 7M one. Don't quote me on that until he verifies it though.

Never said any such thing...

 

[Dan_Gyoba]

Uh...

Stock redline on a 6M crank 7M-GE/GTE is 6500 RPM. Stock redline on a 7M crank is 6250, so the 7M crank gives a LOWER redline than the 6M crank. (Not sure why, as it seems that it should be BETTER with the counterbalance, but there's the data as Toyota put it out.

It still seems to me that the major limiter has got to be the valve train.

 

[IBoughtASupra]

Never said any such thing...

Whoops. Was it you that had a 7M crank modified or a 6M crank? I think I am confusing something here.

Edit:

http://www.supramania.com/forums/archive/index.php/t-103060.html

That is what I read. I just did not remember it correctly and forgot the "never as smooth as a 7M crank" part.

My bad Ian.

 

[CajunKenny]

Valve springs will be the major fail point.
(1st hand experience)

What are some of the details behind this failure?

Fresh bottom end? I know you have a million of these Kenny, which one? Stock or the cheap motor that had aftermarket rods and pistons in it.

This is the original motor that came in my 91. It has 160k miles on everything except the bearings. All other aspects of the motor are stock. Valve train, rod bolts, etc...

It still seems to me that the major limiter has got to be the valve train.

Thanks for the input Dan.

 

[IBoughtASupra]

I would assume that the valve springs are weak after so many years. Ian knows I bugged him about my motor sitting so long and the valve springs were loosing tension, after running, it was fine.

The COMP springs are what a lot of people use as they are cheap and fit the 7M head.

 

[IJ.]

8300 rpm just about everytime I drove it, Ferrea Dual springs, Ferrea OS Valves, Ti Retainers, Shimless buckets..

Got the replacements Cryo treated no more failures.

Rod Bolts would be next on the Hit list.

Then Rods.

Will all depend on how it gets driven, my car would see long pulls at high rpm to high top end speeds.

 

[IBoughtASupra]

http://www.supramania.com/forums/showthread.php?55363-7MGTE-VALVE-SPRING-ALTERNATIVES

 

[CajunKenny]

Well, I certainly don't plan on running to 7500 for long periods of time. Just in between shifts. Thanks Ian.


Andy: Kudos for the link. It seems that Jegs has the comp springs for $24.99 per 12. Not too shabby. I currently have a set of ferrea dual valve springs to go in my next head. Although, they have been reported to have excessive bind so they'll have to be checked to see if they can even be used. That's for the next motor though.

 

[MRSUPRA]

You don't really need to rev it out to 7500 rpms with a JT62 turbo. (I'm guessing that's a bolt-on turbo to the stock exhaust manifold). It's not like it's a huge turbo with a big A/R that spools very late.


Anyway, I think all you really need is better valve springs. I reved my built 7M to 7300 rpms with BC upgraded springs and retainers.

 

[CajunKenny]

Just for reference: The JT62 has a 61.5mm .70 A/R Cold Side with the Boss P-Trim Hot side. I don't remember the A/R of the hot side. I wish I did...

It's at full spool right around 4k. And yes, it bolts to the stock exhaust mani.

 

[AJ'S 88NA]

I would build with a little larger bearing clearences than stock.

 

[Greyscorpion]

If you are wanting to spool faster and rev higher I would def focus on the head I would go with larger valves and like 264 or 272 cams. You will def spool faster with the cams upgrade

 

[Nick M]

Uh...

Stock redline on a 6M crank 7M-GE/GTE is 6500 RPM. Stock redline on a 7M crank is 6250, so the 7M crank gives a LOWER redline than the 6M crank.

It isn't the crankshaft.

It still seems to me that the major limiter has got to be the valve train.

Exactly. I would have thought the BBC inner was a more common upgrade.

 

[IJ.]

It isn't the crankshaft.



Exactly. I would have thought the BBC inner was a more common upgrade.

"Cheaper" upgrade... still a single spring and it you break one revving the engine hard you lose the engine, if someone is serious about punishing a 7M I'd say good duals and light retainers are a must.

 

[IndigoMKII]

IJ could you recommend some valve train upgrades that you'd suggest for a 7500-8000 rpm 7mgte?

 

[supraguy@aol]

Yeah, I swapped out my 22+ yr old springs with some Comp BBC inner's, just to get proper tension back.
Never had an issue with them of course, and I do think it's a common AND cheap upgrade, but as Ian points out,
Not for a true higher rev motor. I consider the BBC springs are to the valvetrain, as Eagle rods are to the rotating assembly;
it's the next step up the performance chart from stock, but you could go alot further, if you plan on making real power.

 

[NashMan]

7200 on my car with a bc springs and retainers, 7200 is about as high as I wanted to go to on stock valves. Stock valves love to wiggle at that high of rpm even with good springs.

when my motor is fixed and the new head goes in I am putting in set of after market valves in bc or ferrara either or will do the job well

so I can rev to 7500 to 8000