Another "How much will it make?" Project "Special Needs"

[CGT]

Took Randys advice and specced a cam based simliar to what he mentioned.... 232-252 110LSA .403 Lobe lift on both sides. Planning on 1.6 intake, 1.5 exhaust. I will most likely play with ratios on the dyno. I'm hoping to dyno in January with some luck.

I have a hex adjust chain set and timing cover to more easily test cam position while dynoing, didnt see alot of other recommendations but id possibly be willing to test someone elses recommendation if time permits. Maybe the speedtalk community could collectively chip in for cam number two? For the quest of knowledge?

[RevTheory]

May I make a prediction?

You'll move that cam fore and aft until the cows come home. Rocker ratio on the exhaust side won't seem to matter either. Hopefully it isn't too bad. My best of luck to you, of course.

[CGT]

May I make a prediction?

You'll move that cam fore and aft until the cows come home. Rocker ratio on the exhaust side won't seem to matter either. Hopefully it isn't too bad. My best of luck to you, of course.

As in moving the cam wont show changes? I gotta pretty good idea where its roughly going to wanna be.....but only testing it will tell the tale.

[CGT]

May I make a prediction?

You'll move that cam fore and aft until the cows come home. Rocker ratio on the exhaust side won't seem to matter either. Hopefully it isn't too bad. My best of luck to you, of course.

Your cam 238-248 108. 4 deg advance
15 IVO
43 IVC
56 EVO
12 EVC

My cam 232-252 110. 4 deg advance
10 IVO
42 IVC
60 EVO
12 EVC

Both cams look farely similar, when comparing valve events. What would make my cam untuneable or unresponsive to cam positon or rocker ratio, as opposed to yours?

[RevTheory]

I think I may have spoken more aggressively than I meant to. My exhaust duration was just a WAG, too. I bet if I had the flow curve clear down to .100, my recommendation would be different. Intake side would likely remain the same but who knows what on the exhaust and it would probably end up even tighter than a 108.

My concern is the amount of flow seen at TDC/overlap. I'm sure it'll make some steam.

Gonna be hitting the pump soon?

[CGT]

I'll see if I can round up some flowz. Hoping to be on the dyno sometime in January.

[RevTheory]

I'll see if I can round up some flowz. Hoping to be on the dyno sometime in January.

That would be cool, even just as a learning exercise between various ways to approach valve timing.

[CGT]

My concern is the amount of flow seen at TDC/overlap. I'm sure it'll make some steam.

Have any idea how lack of overlap flow would show up on my dyno pulls? What data would you be looking at to determine it?

[Rick360]

I'll see if I can round up some flowz. Hoping to be on the dyno sometime in January.

Yes, we need FLOWZ

Rick

[randy331]

Randy, new here, dont have any experience picking cams but I can almost understand 228 jnt. (but for 6000+ ?) also the 112 cl but I cant understand the 20+ more exh duration for a street car w/exhaust .
Is it because of a low i/e percent or to help it hang on longer with higher cyl pressure at both low and high rpm? Please if you want explain. Ive seen 258 at 50/110 on a 496 bbc top at 6300, 267 @ 50/108 top at 6400/ 396 sbc,275@50/108 522 mopar at 6000all had 6-8 deg. more exh.I could never figure this out even with good heads or did they need more duration/ wider cl but these were recommended for their apps. I have read several of your builds and they are very impressive .Just trying to learn a little.
thanks Joe

My cam suggestion had nothing to do with in/ex flowz ratio. I'm not a believer that measured flowZ on a bench tell you what cam to run.

From what I've seen on engines in that cube/rpm range (peak HP at 6500) want a IVC 40*-45* ABDC. So with a reasonable ICL of 106* it'd be 232* duration. But I think the 2.08" intake valve may be a bit big for the combo, so I took a couple deg off for that and a couple off for the comp. Then I've seen EVO of 60* or so still make very good low end power so 60* EVO in on 114* ECL would be a 252 ex lobe.
But when I went back and looked at the 228* on 106 ICL it would be 40* ABDC so I went 112* LSA so the IVC could be in a little later than 40* and still have EVO around 60* and to keep EVC from getting late.

I personally think the cam CGT posted will work very well. It's pretty much where I was before taking 4* deg off the intake lobe.
It'll likely make peak HP above 6500 rpm with that valve size/port size/single plane/cam.

If CGT had picked a 245*-252*-110* cam, would anyone question 252* ex duration?
252* only sounds big when matched to a 228* in lobe.

Randy

[randy331]

I'll see if I can round up some flowz. Hoping to be on the dyno sometime in January.

Yes, we need FLOWZ

Rick

I'll see if I can't find some FLOWZ.

Should I flowZ test the heads with that Tunnel ram ?

Not sure my bench would be able to pull all the air the tunnel ram will FLOWZ!!

Randy

[CGT]

If CGT had picked a 245*-252*-110* cam, would anyone question 252* ex duration?

Good point.

[RevTheory]

I don't know if you plan on posting the flowz or not but do you happen to have the Cd at .100 for each valve?

[CGT]

I don't know if you plan on posting the flowz or not but do you happen to have the Cd at .100 for each valve?

As in window CD?

[RevTheory]

Yeppers