it looks like the low-end didn't change much with the ramhorn, it even looks it picked up a small amount of hp/tq at 4000rpm. after 5000 the ramhorn took off and.never looked back

I would have figured the longer runners would decrease low-end power (like other dyno graphs I've seen) but your setup has amazing low end power

how was initial spool/response changed?
did you coat/wrap the manifold and turbine housing (or use a turbo blanket) on the ramhorn setup?

 

Yes, yes, and yes.. didn't you see his threads and videos. ? you still been under a rock?

 

lol Yeah, the response is a tiny bit "Laggier" but not much. The manifold is wrapped on the upper section basically to keep the hood cooler, it has a turbo blanket, and the downpipe is wrapped until after the oil pan.

 

I was impressed by that too. Ive always noticed those long ramhorn manifolds made lower bottom end power, but big gains on the high end compared to log style ones.

Thanks for the explanation on cylinder pressures and the like. I was making an assumtion that an ls head would be cammed for high rpm operation compared to stock, but even then you cant really compare it to a vtec head since they flow so much better.

Makes sense though. To get 400hp on an ls head youd more likely than not be reaching peak power earlier than a vtec head, which also would require more torque to net that power at a lower rpm. Is that right?

 

I read his thread when he did all of the revisions, I see so many threads they start to blur together lol

maxwell, i'll do some math and confirm that last part of your post... once I go back to sleep and wake up lol

 

My cars always made peak torque around 7k as per the graphs





That last red graph hit boost cut at 33lbs

 

I did some dirty math using the horsepower formula.

To get 400hp out of a lower rpm range the ls has (say 5500rpm), it takes something like 50+lbs more torque than a vtec engine at say 6500rpm.

So a lower reving ls requires higher torque (and combustion pressure) to achieve the same horsepower a higher reving vtec engine makes.

I dont know if I did the equation right though. I sort of guess solving for x where x equals torque, then reversed and plugged my answer back in for x to see if it matched up properly

I should also say the rpm numbers were a random two I picked as comparison. But I do know that ls engines run out of steam around 6k or so unless theyre cammed and ported a bit. Vtec heads go quite a bit higher before running out of breath

 

Has not as much to do with the head and alot to do with the packaging of Intake manifold / Exhaust manifold / and cams. My head has no port work and carries power past 8k

 

Yeah theres that too. My head and cam setup should make power past 8k if I use the right intake an exhaust manifolds. I was going off the basis of stock vs stock. Once you start putting hotter cams and better intake setups on an ls the powerband can be raised quite a bit, but so does the cost.

 

No more then going vtec or getting vtec cams

 

This is true. But I think thats why for some its just easier to swap a vtec head. by the time you build up an ls head to perform similar to a vtec head youll have just as much, maybe more depending on choice of parts, than a stock vtec head.

Since we've been on the subject of torque and vtec vs non
Generally people say not to exceed 400-500hp on stock sleeves, but that just sounds like a crap shoot since its torque that causes the excess cylinder pressure that cracks them (right?)
It seems that a vtec head (or non vtec built for higher rpm power) would be able to make more power by shifting the torque higher up in the revs compared to making the same power on a more stockish ls head that peaks earlier, since it takes more torque o produce those hp numbers.

Have you seen anyones torque numbers on a build that split the sleeves? If you have, what sort of peak torque were they hitting.

Or is it more of a matter of how the torque curve ramps up? Since it seems an engine that has torque build up and hit like a freight train would cause more cylinder stress than one that appears smoother and more linear.