Dyno Question?

[Guest zfan]

I purchased a cam and intake and was wondering if someone would crunch number on this build combo.

 

350 four bolt bored .30 over

cast steel crank

eagle rods

10.25 to 1 compression

Comp cams xr276hr hyd. roller cam

222/230-505/510 with 110 lobe seperation

1.50 roller rockers

Weiand stealth dual plain intake

Holley 750 double pumper

Pete jackson gear drive

Msd mech. advance ign.

hooker super comp. long tube headers

2 1/2" dual exhaust/two chamber flowmasters

 

Comp cams says this cam is a 1800 to 5400 cam

making 385 ft. lbs. of torque at 2500 rpms.

 

This should help with 700r4 and 3.54 rear gears.

Tires are 235/60-15's. I have drag radials in this size due in tomorrow!

 

Mike

[Kevin Shasteen]

Mike,

 

DD2000 says/Drum Roll Please:

 

RPM's..HP...Tq

2000..145..380

2500..188..395

3000..233..407

3500..286..429

4000..338..443

4500..384..448

5000..418..439

5500..435..415

6000..437..382

6500..420..339

7000..395..296

7500..366..256

 

Mike, in your other post"Cam/Intake Changes" you mentioned "Lack of Traction"....what did you mean by that-were you referring to "Wheel Spin"?

 

If you had lack of traction w/your current intake & cam-you may need to address the lack of traction issue prior to making any cam/intake changes.

 

Just something to think about.

 

Kevin,

(Yea,Still an Inliner)

[Guest zfan]

Kevin, What I meant by traction problem is I currently have lousy/cheap 235/60-15 radials..Pep boy specials. I have to launch at Idle or risk major wheel spin with even weak motor. I need drag radials so I am buying a pair this week.

 

Discount tire was out of stock and has ordered them. If I launch any higher than idle it is a waste of time as my times get even slower.

 

My current set up my best guess with traction and no passenger would be low 13's. My times I posted in cam/intake changes were with 2 people in car and very limited traction.

 

Mike

[Guest zfan]

Kevin, Forgot to mention the heads are Edelbrock Rpm's 64cc, 170 intake runners. But you already know that.

 

DD2000 is interesting as Comp cams shows on their dyno sheet that max torque is at 3700rpm's and max horsepower is at 5200rpm's.

 

Thir engine tested is 355 30 over

9.25 to 1 compression

sportsman 11 heads

edelbrock rpm intake

750 holley 3310 vacuum secondaries I believe.

1.5 roller rockers

1 5/8" headers

 

Comp cams lists dyno and specs on their site.

Found it really interesting the differences in the two?

 

Mike

[Guest Anonymous]

May I ask a naive question and please make it a brief answer and if you can use small words even better. haha

I know everyone (I think they do) shifts at max HP RPM, but if torque peaks out earlier, are you still gaining momentum winding it out past max torque curve? Or more simple, should you shift at max torque and not HP?

 

Regards,

 

Lone

[John Scott]

Originally posted by Lone:

May I ask a naive question and please make it a brief answer and if you can use small words even better. haha

I know everyone (I think they do) shifts at max HP RPM, but if torque peaks out earlier, are you still gaining momentum winding it out past max torque curve? Or more simple, should you shift at max torque and not HP?

 

Regards,

 

Lone

Best shift point rpm will be where the least change in torque between shifts occurs. This will be gear specific. Great shift point calculator on Prestage.com.

[utvolman99]

Lone,

thats a really good question. The factors that go into shift point have to do with both your torque curve and your transmission gearing. As I understand it is recommended to shift so that you will be at the peak of your torque curve in your next gear.

With a 2.95 first gear and a 1.94 second gear (GM T-5) and 3700RPM Max torque. You would want to shift at 5626RPM. That would mean that you would be at 3700RPM and max torque after your shift.

 

(Max torque)/(2nd gear) = (Shift Point)/(1st gear)

 

Shift Point = (3700RPM/1.94)/2.95

[Kevin Shasteen]

Originally posted by zfan:

.., DD2000 is interesting as Comp cams shows on their dyno sheet that max torque is at 3700rpm's and max horsepower is at 5200rpm's..,

Mike,

 

For starters, DD2000 is probably about 20-35 hp/torque to high-it usually is. But this doesnt mean we should throw out the baby with the bathwater..(where did that saying come from anyway?).

 

There is something amiss that your engine builder has done (that we are not aware of) in relation to somthing that Edelbrock didnt do in their dyno test engine, something-somewhere, that has skewed our outcome compared to Comp.Cam's outcome.

 

Your Performance gains will improve when you first solve your traction issues. Also, a cam with lower duration and a 112 LSA will also improve your Street Performance at lower rpm's as your torque curve wont come on so fast: which has a tendancy to break the tires loose/good or bad tires it doesnt matter.

 

If nothing else, a cam with slightly lower duration and slightly lower lift will drastically improve your low rpm power.

 

If you want extra torque in the true "Low" rpm's (2500-3800rpm) then you will need a cam in the 260, 265 duration arena. Once you surpass the 270 Duation-your peak #'s are going to be reached on the upper rpm range; period/what can I say(?). As Duration is increased so to will the rate at which peak hp/torque be reached also. This higher Peak Power/Rpm (as you know) comes at the sacrifice of low rpm power.

 

You still need to address the "Lack of Traction" first; then and only then will you truly know what your engine is or is not capable of.

 

If you are running high 13's and that is with excessive wheel spin/then there is no telling what gains can be had once you eliminate that wheel spin; instead of more rear gearing-how about less gearing to eliminate so much torque at the rear wheels. This will offer more launching ability w/out wheel spin, and that translates into an improved 1/4 mile times.

 

Keep us apprised of how things turn out.

 

Kevin,

(Yea,Still an Inliner)