Ron, could u tell a difference on how much faster your motor rev'd out with the HPR4's vs the 109's?

 

I had some other issues that were hurting my HP4's past 7000 rpm but I revved noticably quicker to 5000 rpm with the HP4's. We are doing a dyno session hopefully tonight, maybe tomorrow on a stock bore alcohol DS that we removed 109's and are installing my HP4's to compare the difference. I will be paying attention to what hp at what rpm and also elapsed time from 2000 rpm to 8500 rpm. My experience with these cams on my bike has been purely seat of the pants and in the context of my porting. What we are doing hopefully tonight should be fairly scientific since the only thing we are changing is the cams. I expect similar results to mine since this guy has the same head I do. The reason we are doing it is he can't believe there is a cam out there that will give massive bottom end and massive top end without sacrifices. I think my new cams do just that so we will see.

I would be interested to see Mario do the same test with his porting and see what the results are........

Ron

 

 

I can hear Randall chuckling behind his computer screen when you refer to me as an expert. Randall is a friend and he knows how little I actually know. Actually ERBE seems to know that to, LOL.

I seem to recall Mario having a close friend with some HR3's that I think are sitting on a bench somewhere down in Nevada right now............

Well the pressure is on. I hope my buddy doesn't change his mind about testing my cams now that I have shot my mouth off.

Ron

 

I've seen plenty of those hpr dyno tests i'm sure those cam vs cam ones are around, capewindy had a book full, just start asking i'd be suprised if you can't find what you want to know.

 

Ron, Your right about the combination. My last 730cc motor was assembled by the preacher. He is a top fuel funny bike builder and he builds them literally fron the bottom up from scratch. He knows his stuff and he is like a scientist. He matched my porting with valves, Degreed my cams to the fullest, angles valves and somehow made the bike put out a ton of torq very early. As a matter of fact this same motor with a ron wood pipe and tm 48 dynoed at 55ft lb torq on a huge drum diesle dyno... My buddys raptor 800 got 45ft lb torq. This is all with the super heavy je piston at 570 grams.. Then what added even more torq was the hpr drag pipe. I now have the stage 2 motor with the a-1 a-2 cams. This head has a good port job. I am willing to test anything on the dyno as long as if it makes more power I can keep it for the hassle[img]i/expressions/face-icon-small-smile.gif[/img]

 

Ok, I just got an unbelievable phone call. My HP4 cams in this stock bore alcohol setup made a tremendous increase over the 109's. Before I tell you what the difference was, I want you all to remember the conversations we have had about the biggest gains coming from solving the bottle neck in your build that allows your other mods to function at potential.

I promise on my honor that this test was not rigged in any way. We swapped cams and did no tuning. The bike on 109's peaked at 58 hp. The HP4's peaked at 79 hp. stock bore, stock stroke! on alcohol and 10% NM. We have seen as high as 64 hp with 20% NM on the 109's but we were 10% NM for both runs comparing the cams.

Our porting is good. Everything is good, we just needed our cams to allow more flow.

Some more good news is the acceleration from 2000 rpm to 8500 was 1.5 seconds quicker!!!!! Guess what that is going to do on the hill!

Ok, I know a bunch of you are going to cry BS! I hope to have the dyno sheets to post tomorrow. Even that won't convince some of you, but those of you that do trust my honesty can take this for what it is worth in your cam selections.............as long as you have a good race head. With these cams in this motor we will be pushing about 84 - 86 hp at 20% NM is my guess............653cc!

Btw, don't look at the peak numbers, look at the difference. We may be 5 hp + or - different than we would be on anyone else's dyno. This is still a huge compliment to HPR!!!

We are still working on dialing in the carb which should improve our numbers a bit. Eric and Randall I am even more of a believer than I was before!

I will keep you posted.

Ron

 

I just want to be clear on this... was there a 20hp difference between these cams? That is incredable if it is accurate.

 

Yes. With no tuning there was 21 hp difference and we had a flat spot or slight dip in the torque curve that is costing us some hp or the difference would have been greater.

Remember much of this is because the 109's were a bottleneck. The rest of the setup wanted to move much more air and fuel than the cams would allow. This is why matching componentry is so critical. There is huge hp to be gained or lost when you mix and match parts vs mapping a build to really work well.

There is not 21 hp difference between cams alone. Part of that gain was because our setup happened to be much better suited to HP4's. Not everyone will see gains like this unless you really open your heads up to handle a ton of flow beyond what 109's can handle. This is the only conclusion I can come to based on what is happening here.

Ron

 

20 hp on cams thats a big number, eric is a good builder but i never knew his cams were that good. it was just a cam change?