[ModMustang97GT]

I have a 97 GT, and I am considering getting the Logan Motorsports intake. I want to know, since the intake is good to 7000rpm. What is my engine good to. Will my rotating assembly be able to take that? If not, I expect a good stroker kit would be fine to 7000RPM, despite the bigger stroke. But I just wanted to know if anyone knew what the limit was, I know according to the tach its 6K.

[Juggalo_X]

if its a stock engine with stock internals then its the stock rpm limit. Revs are limited because of vibration in the crank and such at high rpm. exceeding this could cause bottom end damage, or top end damage like a collapsed valve spring ect.

[acmillr]

The stock assembly is pretty decent to 6500 and even a little more from my experience. The stroker kit will be worth less RPM's than a stock stroke set up for sure. I wouldn't push a stroked modular much past 6500, but that's just me. On the other hand, a built stock stroke 4.6 will scream over 7000 all day.

[mdvaldosta]

You got cams and heads that'll breath that high? Don't matter what you can rev to, matters where you make power. Stock bottom and top end is good to around 6500 fairly safely, but you won't make power anywhere near that high without heads and cams.

[acmillr]

You do have the PI heads, right?

[07stanggt]

Can somebody explain to me why these engines cant rev higher? I thought one of the pros of ovc engine was higher revs? I see pushrods reving to 8 thousand on production cars like the vette and cup engines in nascar hitting 9000. Why is the stock rev limiter at 6250? and your saying if i get forged parts it still cant go over 7000?

[Juggalo_X]

things like a better balanced Crank, lighter and balanced drive shaft, better cams and springs all will allow a higher rev with out the engine vibrating its self to death internally. its all about the vibrations and the tolerances for the installed parts. that and u need valves heads and an intake that will be able to flow at that rpm.

[Juggalo_X]

forgot to mention a lighter fly wheel. and if they make one for our cars a hydrologic one would be preferable so its always perfectly balanced

[acmillr]

Nobody said that you can't rev over 7000. I shift mine at about 7300. However, you are shooting yourself in the foot if you are trying to build a stroked motor for high revs.

[07stanggt]

Originally Posted by Juggalo_X things like a better balanced Crank, lighter and balanced drive shaft, better cams and springs all will allow a higher rev with out the engine vibrating its self to death internally. its all about the vibrations and the tolerances for the installed parts. that and u need valves heads and an intake that will be able to flow at that rpm.

Ok so its a lot to do with other stuff than the engine itself. That makes sense.

[Juggalo_X]

Originally Posted by 07stanggt Ok so its a lot to do with other stuff than the engine itself. That makes sense.

yep

[ModMustang97GT]

The stroker kits are built to a higher standard and forged so they are stronger. The 2 main causes of vibration in the engine are balance and give in the materials. The stock crank is no where near as well made as a stroker kit one, so the materials are not an issue. The only issue then is balance, and an experianced machinist like the ones we use to balance our Hydroplane engines, can balance the crank to turn unreal numbers. At any rate, I know I could crank the Stroker higher, I just wanted to know if when I swapped in my new heads and intake, if I can really tap in to the potential of the intake with the stock crank, rods and pistons. And it sounds like it won't very well.

[96Snaker]

Originally Posted by ModMustang97GT The stroker kits are built to a higher standard and forged so they are stronger. The 2 main causes of vibration in the engine are balance and give in the materials. The stock crank is no where near as well made as a stroker kit one, so the materials are not an issue. The only issue then is balance, and an experianced machinist like the ones we use to balance our Hydroplane engines, can balance the crank to turn unreal numbers. At any rate, I know I could crank the Stroker higher, I just wanted to know if when I swapped in my new heads and intake, if I can really tap in to the potential of the intake with the stock crank, rods and pistons. And it sounds like it won't very well.

Balance balance balance. And what Joe said - there's no need to rev that high anyway, as your power band will come much sooner than that of 8, 9K I can only assume.

Whoa you work on the SeaFair Hydros? That's pretty cool!! Whereat exactly? If you don't mind. I just noticed you were from Seattle.

[Trick Tuners]

As some of the others have said its all about having a proper combo with all the parts matched. Your intent also matters. For example if you want a high revving NA beast for the track or something with a lot of boost for the street. If you get a cam set up for lots of power on the high end it will be a dog on the low end. Intakes are similar due to runner design. If it can flow 700hp and you only have 300 you will be missing out on hp and low end tq because the runners will be too short and wide. Its all about keeping the air velocity high without restricting the flow. (if you oversize you can loose power) More valves also help with revving higher. (4v)

[ModMustang97GT]

I live in seattle, I work with both Lealand Racing and Unlimited (the big ones) and Miss Critical Logic which is a UL which I am actually on the crew for. Anyways, I would love to have a car that will make 300-400 hp at the wheels. 400 would be excelent, but I don't want to get a Centri charger. I would like to go turbo or Whipple\KB. The problem is, those are both really expensive. I can grab a good intake and it will save me alot more than buying a SC. Granted I will get 50 -70 more HP than the N/A intake. But with the N/A intake, and a good n/a cam, I can crank it up to around the 350 whp mark. But if my internals are going to crap out about 6500 rpm, its hard to make the N/A work really well.

[johnr2001]

4.6's are known for spinning rod bearings. A stock one will not take 6500 for long with out doing so. unless your changing your intake it stops making power at 5800 anyway.

[1slo5.0]

Originally Posted by ModMustang97GT I have a 97 GT, and I am considering getting the Logan Motorsports intake. I want to know, since the intake is good to 7000rpm. What is my engine good to. Will my rotating assembly be able to take that? If not, I expect a good stroker kit would be fine to 7000RPM, despite the bigger stroke. But I just wanted to know if anyone knew what the limit was, I know according to the tach its 6K.

RPM means nothing. If your engine isn't making any power at that rpm your car is going to slow way down. Just because the intake is advertised to have a 7000 rpm limit doesn't mean your engine will make power at that rpm or even benefit from the intake.

[StangAddiction]

Originally Posted by acmillr Nobody said that you can't rev over 7000. I shift mine at about 7300. However, you are shooting yourself in the foot if you are trying to build a stroked motor for high revs.

+1...if you want a hi-rev motor go with a big bore setup..

[acmillr]

Originally Posted by StangAddiction +1...if you want a hi-rev motor go with a big bore setup..

I have been considering a 3.700" bore for my next build. I feel like that would be the way to pick up some much needed cubes.

[acmillr]

Originally Posted by johnr2001 4.6's are known for spinning rod bearings. A stock one will not take 6500 for long with out doing so. unless your changing your intake it stops making power at 5800 anyway.

Actually, the stock intake makes power to about 6700 and starts to fall off.