cam grind question/specs

[dohcfiend]

500 is a little much for a cam grind. but i would probably use chrfab anyway b/c it seems like they have a good reputation with making power.

i wanna throw this out there. i might have $250 to spare, what would be the result of having my intake cams reground but leave the ex cams stock in a 96 motor?

also does any1 have the w41 specs? and does any have the 96-97 specs(i noticed alot of question marks in the specs section for the 96-97)?

[SappySE107]

Desktop dyno would tell you as much as I can about what would happen with doing just the intakes. Oddly enough, I was thinking of doing just exhaust.

W-41 specs might be in the 7 page cam thread.

[Cannonball]

Normally it's better to favor the exhaust than the intake when it comes to GM engines at least. I'm not sure if this is still true on a multi valve engine as well or not tho. I think it's a safe bet that you'd be better off with more exhaust than intake. If this was a pushrod engine, that's how you'd have to do it. Whether or not a multi valve engine will act the same way or not is a good question.
I guess this sort of lets the cat out of the bag on what I was thinking with the TDC engine and custom cams. On a pushrod V6 I have noted that when you use a single pattern cam you only add a small ammount of power on the top end and actually, many times, hurt the low end somewhat. When I read the custom cam thread on this site it got me to thinking that the custom cams tried were all using the same numbers on both the intake and exhaust cams and they showed a loss at lower rpms. My thought was; what if you used a different intake cam and different exhaust cam thus having a split pattern cam basically? This should, if it reacts anything like a pushrod engine, make power in the midrange and top end while still retaining the low end it always had.

Something else of interest when using the W41 cam specs I noticed. The lift of the W41 cams is .410 which coincidently is also the exhaust lift of the pushrod 60* V6. My thought was to try a .394 intake cam for the TDC and a .410 exh. cam for the TDC on desktop dyno and see what happens. Those figures are the exact lift figures of the 60* pushrod HO cam. It hadn't crossed my mind to just increase the exhaust cam alone and see what happens though but that's a pretty damn good idea. You'd only have to pay to have 2 cams done then rather than 4 that way.
Thoughts? Comments? Rotten fruit to throw?
Edit to add W41 specs: 218 @50 duration and .410 lift on both intake and exhaust cams.

[dohcfiend]

i am not sure if i want to touch the lift though. my motor is already an interference motor. i wanted to play more with duration. perhaps i will spend my dough elsewhere, can't go wrong with an underdrive pulley.

but i like your idea about making it a dual pattern design though. perhaps 218 intake and 226 exhaust duration?

[ez112]

I really like the idea. Excellent suggestion, Cannonball. Hopefully the specs you come up with will proven to be useful on Desktop Dyno. Not to mention half price for cams!

[Gemmer]

peaked my curiosity

I punched in just the exhaust cam (that the shop said they could give us) into DD

about 5 hp lost untill 4,500 RPM where it levels out, then it climbs to its peak at 6,000RPM which is about 25 hp over stock peak HP...then power starts to recede...

but it doesn't recede nearly as fast as a stock vehicle...just because of the rate the stock cars power falls off, at 7,000RPM, the cammed one makes 30+ over what stock does at 7,000rpm.


it does move our peak hp up a bit...BUT when you consider even at our old peak (5,500) it still makes 10 more hp than stock, not too shabby

Of course this is just DD so take it with a grain of salt till someone actually does it...It wouldnt supprise me if in real life its not worth shit But it seems to be a fun start!

BTW, the lift didnt make much of a difference

[dohcfiend]

i have always wondered about the DD. i don't believe it to be too accurate b/c it has 1 4 valve head profile(which i believe to be based off of a 4 valve v8 head) for everything. if some1 could get the necessary airflow data instead of using default i believe it would be alot better.

as far as building v8's with it i believe it to be fairly accurate then.

[Gemmer]

we are using a flow file a guy with a 3.4 DOHC made. (I think he drives a fiero)

As far as the files we are using, it shows the stock HP curve pretty damn accurately. It peaks at 210 right at 5,500 and fallsoff perfectly along with the 3.4 dynos Ive seen...however the torque is off, which is why I never say the torque results it pops out.

But I agree, I tend to look at it as a general overly optimistic start, but still a start none the less.

[Cannonball]

I'll try to post this again since it didn't work the first time:
Try using the 394 intake lift, 211 duration on intake, and 410 lift on exh. with 218 degrees duration on exhaust on DD and see what you come up with.

[Cannonball]

I ran the numbers I posted above thro DD. Interesting, gained 40 HP up high and 3 LB Ft as well up high but there are losses in the lower range. Interesting if you look at the graph, if you run these numbers yourself, you'll see a much better curve throughout the rpm range. Ths stock engine rises quickly down low but also falls off quickly. My cam numbers give it a nice flat linear curve. This might be worth doing. I've got a few other ideas/numbers to play with yet but this looks like it might be going in the right direction especially if you have a stick.

[Gemmer]

they look good..interesting if you average the HP numbers removing the peaks (which I always thought could be missleading)

Assuming this is for strip more than anything, and we launch at 3k rpm, it seems logical to average hp from 3k to 7k to see our average powerband.

stock cam averages....................182 HP

13* retard..................................192

Shops specs exhaust only............194 HP

Shops specs...............................195 HP

W41 with Shops max lift (.384)....195 HP

W41 Cam Specs.........................197 HP

Cannonballs specs......................198 HP

even if we drop cannonballs lift to shop spec for safety (.372I .384E)

.................................................. 196

but can we get cannonballs on a regrind?

Out of curiosity, in and auto and manual, when we shift from 1st gear to second going 7krpm, what RPM does it drop down to

[Gemmer]

ide be interested in seeing what interesting combos we could get just by changing the timing on the intake side and getting a regrind on the exhaust side

[Cannonball]

The safety thing is something i'd like to know badly too. How much lift is safe to use on these engines? I've asked before but nobody seems to know. I know you can deck the heads to a certain ammount (12 I think?) but that doesn't tell me how much lift you can safely use without hitting. Unless there's some math equation to figure that out but that would make my head explode since i'm no good at math.
Anyone?

[dohcfiend]

well, the 91-95 setups are non-interference, so i guess you can use more lift than on a 96-97. of course that doesn't help you much but that is all i got

[Cannonball]

It does help somewhat seeing as how I'd like to use a 95 motor if i decide to swap a TDC into my car.
I played around for a shorty time last night with DD and noticed there's little effect from lift on HP or torque numbers. That definitely leads me to agree with Gemmer above about the torque being off with this program. Just to test the program, I put in a lot more lift on both intake and exhaust and there was almost no difference.
I also played around with durations and leaving the lift mostly the same and came up with more torque down low. I'm going to do some more testing and post the numbers so everyone can try it and check it out. Only bad thing about these tests is that the lift is showing very little difference when it should show a difference. My thought is, I think there's actually more torque from these figures then the program is showing which is a good thing.