Topic: High RPM durability-what next?

[snorth88]

Hello,

My new build so far:
18 HP Vanguard
Thinner Head gaskets, mildly ported exhaust with restrictors removed
2 barrel carb with high flow intake and air filter from EC carbs
Rev kit with timing advance key, Iskenderian valve springs & Cheetah cam from Precision

Ok its runs good now that I've got the proper main jets in it, it could now rev past 5500rpm, but It was said 5500 is redline for this setup and now of course I think I need to go faster.
Can anyone suggest what I need to do next to allow turning of higher RPM's safely and what could I safely rev to with your suggestions.  ( I need to keep charging system)

Thanks for your input!

[cycloneracer]

Stock flywheel?   I wouldn't stand in the same county as it at 5500RPM. 

You need a billet flywheel.  Steel or aluminum. 

I don't know of any that allow the charging coils to be used. 

Your also probably overcharging at any RPMs over stock. 

[slideways]

We run stock flywheels in our class upwards of 6500rpm with no issue.. that's with stock charging too. But i would recommend going billet for tuning and for the torque increase. I'd say your limiting factor is the stock rods and pistons... or at least for sure the stock rods.. I dont think many are turning too far over 5500 with stock rods. Once you go billet you can turn it 7000 without much worry.

[snorth88]

Thankyou I will look into these things as my next improvements.
Anyone know how much extra torque and/or hp one can expect going with a safer billet flywheel?
Looks like EC has a direct replacement billet flywheel that retains the charging capabilities and improves the output by 17% 

[Todd99]

You should never turn a stock flywheel over 3650 rpm's that is asking for a lot of trouble and people getting hurt!!! The billet flywheel should have been the first thing you bought when you took the governor off the motor!!!!!!!!! I would highly suggest buying a billet flywheel before doing anything else!!!! Please don't leave the stock flywheel on it!!!! Like Paul said I don't want to be anywhere near you turning 5500 rpm with a stock flywheel and to the guy that says he is turning 6500rpm with a stock flywheel that is just plain crazy you will have problems!!!!

[PJG56]

Looks like EC has a direct replacement billet flywheel that retains the charging capabilities and improves the output by 17% 

There will be no charging capabilities to my knowledge.The 17% improvement would be spark output ignition wise.

[Gui961]

I dont understand so much fear of the stock flywheel. 100% stock engine if the governor fail will rev to 4-5000 rpm before floating the valve i would guess Briggs build them with a safety margin or it would be a major liability for them... problem is dumb people trying to make them lighter. i'm sure there was never a issue with 100% stock ...

I'm going to guess this tread was never about racing lawn mower since we dont need charging system.... and the build was done wrong from the begining cheatah cam as a peak power at 6500. and there you need a billet arc flywheel for sure and  billet rod or you will pick parts outside the engine .

[cycloneracer]

I dont understand so much fear of the stock flywheel. 100% stock engine if the governor fail will rev to 4-5000 rpm before floating the valve i would guess Briggs build them with a safety margin or it would be a major liability for them... problem is dumb people trying to make them lighter. i'm sure there was never a issue with 100% stock ...

I'm going to guess this tread was never about racing lawn mower since we dont need charging system.... and the build was done wrong from the begining cheatah cam as a peak power at 6500. and there you need a billet arc flywheel for sure and  billet rod or you will pick parts outside the engine .

I agree most will not explode.   It is the one that does is the problem. 

We are talking about doubling the rated RPM's   We are the only Motorsport on the planet that thinks this is OK.    Or would even try this. 

[slideways]

In a class that has been around since 2000 running stock flywheels at that rpm with never a single failure. It wasnt until 2012 then the ARC was allowed for competition. I agree that its not the smartest idea and the ARC is a no brainer to use in 90% of cases. I run the ARC on all 4 of our engines but in certain cases the steel one has its advantages. To answer the torque question its typically a 2-3ft lb gain simply by bolting the ARC on vs the 16lb Steel unit.

[berthyd]

I agree most will not explode.   It is the one that does is the problem. 

We are talking about doubling the rated RPM's   We are the only Motorsport on the planet that thinks this is OK.    Or would even try this. 

Huh?? What's this got to do with the amount of torque an engine produces?

Bert