[BruceWilkie]

Just a easy example of just ONE possibility with a solid flat 302/310 264/272 .675(w/1.8) 113 LSA 2 deg adv. 446 (4.21x4) 12.5 compression. 850 cfm carb. 607 ft lbs near 5500 rpm 741 hp at 7000 dropping to 735 at 7500. Tightening LSA brings power below 5200 up and kills power above 5500. LSA wider than 113 drops power below 5500 and starts to lose a couple hp at 7000-7500
A 1050 carb is good for another 20+ hp and 15 ft lbs at peaks. I didnt spend much time on this and can likely find better. CV1 with 1.71 ex valve 2.125 header.

621 ft lbs 765 hp 12.5 comp 5500-7500 rpm band seem close to what you are looking for??? Not bad for a flat tappet. A smaller 2 inch header knocks the curve down by about 20 numbers.

[TIN TIGR]

my numbers are a bit more conservative, but yes..i could live with that..i think it will be interesting either way

[Skip Fix]

Interesting notes on exhaust size-I know I'll get hit with the "average HP comment, -but look at what the 600+ EM guys were using-few if any 2" , smaller ones mainly and alot of 600+ HP motors.

[BruceWilkie]

Originally Posted by Skip Fix

Interesting notes on exhaust size-I know I'll get hit with the "average HP comment, -but look at what the 600+ EM guys were using-few if any 2" , smaller ones mainly and alot of 600+ HP motors.

Skip, of interest here, when I was deciding cam profile for my Ford and looking at pump gas street type combos I was only losing 10-15 hp on top with the small street type tube modeling, the very low rpm side was up a lot. As it progressed into higher rpm racebands and 13.3:1 compression the large tube models really pick up and lose little below 3000.

[BruceWilkie]

Originally Posted by TIN TIGR

my numbers are a bit more conservative, but yes..i could live with that..i think it will be interesting either way

That wasnt with a lobe as radical as the xtq series. I punched in an appropriate sized xtq and there is possibly another 30 hp but lobe life will be less.

[blaktopr]

When thinking of the reduced LSA, the thoughts of which lobe to move, in respect to IN or EX centerline, or the duration, ramp rate, of each lobe. Each change in cam timing can result in a different engine dynamic even with the same LSA. The exhaust's ability for the blowdown period is needed for the proper exhaust timing. The way the intake port works gives you an indication for the intake lobe. Varying the intake port's flow profile can allow you different valve timing aspects in regards to overlap. The speeds of air at each seat during overlap has a role in cam profile and overlap. So,
Would the exhaust lobe be moved to open the valve later and close it later, or just close it later? Would the intake open sooner or open and close sooner.

I don't know the CV-1. And I don't look at a valve angle at it's ability to scavange because it is angled. I just look at those variables. Kaasse discussed his "reasons" on Speedtalk for a tight LSA. It doesn't work on everything.

Depending on how the head "works", moving the lobes closer can have it's benefits where you can open the EX valve later (depends on how much force is still on the piston and if the port can blowdown fast enough), have it close later and open the IN a little sooner, (as long as the intake port does not promote reversion) and close the intake sooner to build more pressure before the spark.

Try it. Especially if you have a cam around.

[BruceWilkie]

Originally Posted by blaktopr

When thinking of the reduced LSA, the thoughts of which lobe to move, in respect to IN or EX centerline, or the duration, ramp rate, of each lobe. Each change in cam timing can result in a different engine dynamic even with the same LSA. The exhaust's ability for the blowdown period is needed for the proper exhaust timing. The way the intake port works gives you an indication for the intake lobe. Varying the intake port's flow profile can allow you different valve timing aspects in regards to overlap. The speeds of air at each seat during overlap has a role in cam profile and overlap. So,
Would the exhaust lobe be moved to open the valve later and close it later, or just close it later? Would the intake open sooner or open and close sooner.



I don't know the CV-1. And I don't look at a valve angle at it's ability to scavange because it is angled. I just look at those variables. Kaasse discussed his "reasons" on Speedtalk for a tight LSA. It doesn't work on everything.

Depending on how the head "works", moving the lobes closer can have it's benefits where you can open the EX valve later (depends on how much force is still on the piston and if the port can blowdown fast enough), have it close later and open the IN a little sooner, (as long as the intake port does not promote reversion) and close the intake sooner to build more pressure before the spark.

Try it. Especially if you have a cam around.

From my sim testing the cv1(non covertible exhaust) is showing it likes an early fast exhaust opening. The cv1 "Pontiac style" exhaust port flow numbers are NOT an "ideal" 85% port. Opening early and fast greatly aids blowdown. the exhaust flow also affects the amount of exhaust duration required compared to the intake to clear the combustion chamber of residual exhaust during overlap dwell period. The duration splits intake to exhaust so far respond best with 8-12 degrees split in the exhausts favor, with a high ramp rate profile. When using a slower hyd roller the spread is typically around 4 degrees because the seat time effects on the overlap window. (the dynamic compression with the hyd roller and the cv1 leaves alot to be desired) Im finding LSAs usually ending up at 112-113 with ICL from 108 to 113 depending on how you want to shape the power curve. This is with 4.21-4.5 stroke motors looking for power peaks in the 6000 to 7000 rpm range. Trying to lower the peak power rpm with the shorter 3.75 - 4.0 stroke takes a really short intake duration and 10-12 more on the exhaust and the LSA's end up in the 108-110 range. Doing so is counterproductive as it really indicates a lesser flowing head would be the better approach. The cv1 wasnt intended for mild to modest power levels. If you want the most from a CV1 on a small motor you have to up the rpm range. Doing so can be very rewarding IF the shortblock is up to it.

BTW the Engine masters engines are purpose built to get best average hp and tq numbers over an extremely wide 2500-6500 rpm band. Both Kaase entries are easily capable of 100 to 200 hp more with a cam change and reoptimization of the intake and exhaust. I know from talking with Kaases crew when I was getting my 528 parts gathered the "Street Boss" 429 is capable of 900 hp on pump gas.

[TIN TIGR]

yes..i can always swap the heads off later to a real cv-1 built engine..this is for fun and education..

[blaktopr]

Nothing wrong with fun and education. Any info is better than no info. The interpretation of that info is the fun part.

[slowbird]

Bruce how are you simulating a standard exhaust port compared to the convertible exhaust port?

[BruceWilkie]

Originally Posted by slowbird

Bruce how are you simulating a standard exhaust port compared to the convertible exhaust port?

I havent! I'm still waiting on FlowData for the convertible exhaust! (there are a few people involved in various refinements of this head)No one has ordered it yet but it definately has advantage over the Pontiac droop, especially for a race header design, especially in a tube chassis car. I understand it is designed to use same bolt pattern as BBmopar but outboard tube spacing is slightly different.(NBD to section a mopar flange) The lack of the droop allows for better flow by not being confined to casting size and offers the opportunity to have a straighter shot out of the port.

[slowbird]

It will be interesting to see what the Race Shop comes up with once they start working on it.

[BruceWilkie]

Originally Posted by slowbird

It will be interesting to see what the Race Shop comes up with once they start working on it.

a few other reputible shops are as well.