Guys, I dont have a local dyno to go to, but I do have my last time slip.

What kind of HP do you guys think my car is putting out at the flywheel and at the rear?

Car weighs in with me and a 1/2 tank of gas at 3400 lbs.

Last time slip.
60 ft -----1.62
1/8 et-----7.641
1/8 mph---90.02
1/4 et-----12.01
1/4 mph---112.45

The temp was in the upper 70's low 80's at 1200 ft elevation on 93 octane. Most of the time I run a mix of 1:1 93 octane and 110, but not that day.

thanks

 

380 using this calcualtor at
www.FastCoolCars.com
or
2009 DragTimes.com
( or other on-line calcualtors )
That's 475 crank HP.
Nice.

 

Thanks, I know that its usually 20% loss through the drivetrain for an auto and 15% for a stick. I didnt know how it works with a built auto with a higher stall torque converter.

I just need a little budge to get into the 11.90's. Maybe going to 1.6 rr's?

I am still running the stock hood. I guess going to a fiberglass hood would help, but I like the stock look.

Most of the mustangs and LS1 cars at the local track dont expect to loose to a ole thirdgen.

I also thought about adding a NX nitrous kit, but like doing it without a power adder.

 

Doesn't matter about camshaft, gearing, transmission, etc. Flywheel HP means nothing unless you're tuning on an engine dyno. How much power gets to the wheels is what moves the vehicle.

To push 3400 pounds to 112.45 MPH, you need around 377 HP. If you put the car on a chassis dyno, you won't see that number. 377 HP is what the car made in those weather conditions and at that altitude. Providing the weight stays the same, next week, the weather conditions will be different and you'll have a different MPH or you go to a track at a different altitude and you'll have a different MPH.

ProStock cars run the 1/4 mile at around 208 MPH at a low elevation track. In Denver, they haven't broken into the 200's yet. They lose that much HP just because of the track elevation.

MPH is the indication of HP. When tuning, watch the change in the MPH. ET is dependent on traction. You can spin off the line and still get the same MPH but the ET will be slower.

You only need enough octane to prevent detonation. If the engine doesn't ping/knock under load with 93 octane, you won't go any faster using 110 or a mixture. Running an EFI system with a knock sensor, you'll never hear a knock. Only a scan tool will tell you if the ECM is retarding the timing because it hears a knock. Retarding the timing will slow you down.

 

I know the altitude density makes a difference, I didnt get a chance to check that day. I had made a few changes from last time at the track which was 12.16 at 110.** mph. That pass was on a cool night.

I was just trying to be conservative at 375-400 hp rating at the motor. Not that it really matter. I had ran the data through one calculator using the mph/et/weight, but I know that just gives a ball park figure.

I have yet to jet my carb for best mph. I will see how that works out.

On the 110/93 octane mix, I run 40* total timing with 10.3-1 compression and aluminum heads. I would say 93 is safe, but with my exhaust, I cant hear much at WOT.

 

You are pretty close, I have your car at 386 flywheel.. No where near 475 as mentioned above. Also 112 MPH is enough for 12.1's, work on the effeciency a little.. Good runner. That is 386 in actual conditions at flywheel, at lower sea level or DA you will have and see more reflected in your MPH.

Sorry, just noticed your et was 12.01! great effeciency! You are beating your ideal ET, by .1...

 

The NHRA calculator I usehas you right about 388-389 flywheel based on the weight and ET you provided. The thing that does concern me though is that you only pick up 22.5 MPH from the 1/8 to the 1/4. You could possibly meet your 11.90 goal or better with a more efficient converter. JMHO...

 

Question.
What calcualtor do you use that only gives 388 at the crank?
I find it surprisingly low.

 

NHRA. Basically, the ET divided by 5.825 = x. x multiplied by itself 3 times... x * x * x = xy. Then the vehicle weight divded by xy. That's just a rough example. Things like wheelspin, excessive converter slippage, etc. will skew the #'s. My car dead hooks, is about 3650 race weight... the calculator says just shy of 590 flywheel, if you figure about 18% drivetrain loss - which is average, it says about 480 at the tires. My car in fact dyno'd 479.7 when I first put it together.

 

Corral.net, very close.
Your calc 475 is wayyyyyy high.. 475 will get you deep 11s in a 3400 lb car.
My car trapped 126 to run 10.87, chassie dynoed 430 at wheels, calc has me at 540 fw - pretty close would you say. Friends stang dynoed 320 at wheels to run 10.7 @ 124, calc has him at 380 fw x .85 for standard = 323 also very close.
My Vega calcs at 750ish FW to run 9.02 @ 151, very close to where that motor should be.

Figure out a car you know, say a 2002 ram air, 3700 with driver traps 107ish.. Should be close to the 360 or so, keeping in mind they were underrated and making near 300 at wheels stock - SDPP rates stock LS1 crate at 380 FW, all close right.. Or 90s camaro that traps around 95 stock at 3600 lbs will probably be near 245ish, just as they were rated.

 

The converter was new and only had a few runs on it. It should loosen up a little with more runs. Its a Jegs 10" rated at 3500-3800.

My cam is a xr282hr-12 with specs here http://store.summitracing.com/partde...8&autoview=sku Only difference is my cam is cut on a 112 LSA.
I thought about going to 1.6 rr's which would change the lift to .544/.554 range. The trans is a TH350 with 3.73 rear gear and 26" tall tire. Im crossing the the 1/4 line at 6100 rpm. Thats shifting out at 6k.

Like I said in a earlier post, I have not jetted the carb for best mph yet. That could help my mph between the 1/8 and 1/4.

 

I appreciate what you're saying it's just that EVERY on line horsepower calculator I use gives me the same results.
I know there's no substitute for the track and we don't race dynos etc. however for bench racing purposes...
12.98 @ 107 mph w/ 3640 lbs = 330 rwhp based on ET/348 rwhp based on trap speed.
The calculator tell me that's RWHP. Is it more likely to be crank hp?
(Thanks for the thread bluegrassz!)
For the record bluegrassz comes in at approx. 375 rwhp using this calculator.
http://www.s-series.org/htm/calc/hpcalc.htm

 

Absolutley, As said stock manual LS1 cars are dynoing just under 300 at wheels and trap right around 107.. 3700+ lb car. I have seen a few of those calcs you are speaking of that give rediculous figures.. Take my Vega, if those where rear wheel numbers the engine would be close to 1000 hp, Not even capable with the heads I have.. Maybe those calculators are where all these people get those figures who have 500hp, That seems to be the number thrown around alot. A good rule of thumb also is 2 HP per cfm that heads flow on an effecient engine, my 406's AFR's flow 280 x 2 = 560, car has actually trapped at sealevel 128 MPH, Calculator says 564 crank. See the "corral"ation

 

Well im confused?

Quote Stephen 87 IROC "To push 3400 pounds to 112.45 MPH, you need around 377 HP."

Is that at the flywheel or rwhp? Im assuming flywheel.

Quote 87_TA "Figure out a car you know, say a 2002 ram air, 3700 with driver traps 107ish.. Should be close to the 360 or so, keeping in mind they were underrated and making near 300 at wheels stock - SDPP rates stock LS1 crate at 380 FW, all close right"

I am 300lbs less than the 2002 ram air and completely spank them at the track. If they are putting down right at 300 hp at the wheels, then how am I over a second quicker? 300lbs = 3/10ths at best. If they are rated at 360 flywheel hp - 15% drivetrain loss for a stick = 306 rwhp. 300 lbs lighter and 30 more hp wouldnt make up for the quicker et. Just using this for an example.

 

The problem ( as I see it ) with these calculators is that they are approximations at best (as stated above).
I've heard it said that trap speed is a good indicator of hp. Thats seems obvious. It's finding a relationship between that speed and a formula for arriving at the same number.
It's all "bench racing" I know however that is a part of the sport I enjoy. Go to the track, lay down a few passes and check to see how well my combo stacks up against published engine builds. Spending an hour on the chassis dyno would be very enlightening.

 

Using my calculator, I get 374hp at the flywheel... Close enough to everyone elses.

Keep in mind this is average peak hp across the run, not absolute peak hp. Errors like overevving, short shifting, tire spin, and TQ converter slip can rob you more than a few HP based on your 1/4 MPH.

 

I would love to have it on a chassis dyno and do some tunning.

I am by no means dissapointed in 375 fwhp. The motor when TPI was rated at 245. I did nothing to the bottom end except for new timing chain, cam and lifters. I added the AFR 190's which we flowed on a bench, changed valve angles, shimed the springs, a little bowl blending and porting. This smoothed out some turbulance and added a few cfm's. We worked the RPM airgap intake the same way.

The AFR's were milled to 60cc's with a thin gasket to up the compression. I know its better to do it with the piston and deck height, but I didnt want to mess with the rotating assembly at this time.

I have swapped around carbs, played with timing and converters.

I guess for it to be a street/strip car with full interior, steel hood and a stock piston 350. I cant complain.

I would like to get into at least the 11.90's in the hot summer. What do you guys suggest?

 

The MPH, 300LB less and 30 more HP will certainly propel a car from 107 trap to 112! The trap speed is the indicator, A stock 02 is hardly optimized for 1/4mile et, 3.42 gear 2.66 first in the 6 speed, no wgt transfer blah, blah. 107 is good for around 12.4/5's, 4.10's, a little suspension and slicks will get that car close.

MPH is a great indicator of FW HP - as stated by someone else I hold little trust in dyno's either, tune at the track, have fun, go fast. Your car as mentioned if effecient, you are making great use of the HP you have! Thats the better than making big power..

 

Here are the flow numbers the CHP got for my heads. We ended up a little better after we worked them.

AFR 190cc Street Cylinder Heads Dominate!
Chevy High Performance Magazine
Intake Port Flow Test Results
180cc to 199cc Heads

Valve Lift Airflow Research 190
.200 144
.300 208
.400 244
.500 262
.600 261


So would my heads support " 262 x 2 =524 hp" Am I figuring this correct?

 

Yep...
Even more with a high compression build of course, but those are over 100 Volumetric effecient.

 

Yeah, I picked up just changing the converter and going to the Hoosier QTP's. They helped cut the 60ft down.

It is nice to pull up to the LS1's and the 5.0/4.6 mustangs and send them packing.

I have really been comparing my combo to a AFR Dynoed combo.

AFR's Dyno 383
AFR 190cc Street Heads
9.5 to 1 compression
1 3/4 Headers
AFR RPM #5029 intake
Holley 4779 750dp
Comp Cam Hyd Roller #12-433-8 http://store.summitracing.com/partde...8&autoview=sku
MSD Distributor 36* Timing
93 Octane Pump Gas

Dynoed at 503 hp with 517 ft TQ

My combo
L98 350 stock flattop pistons, stock bore and crank
AFR 190cc Street Head with valve/port/bowl work
10.3 to 1 compression
1 5/8 Headman Longtubes
Edelbrock RPM airgap intake
Holley 750 Street HP with 1/2 phenolic spacer to cool carb
Comp Cam Hyd Roller 08-432-8 http://store.summitracing.com/partde...8&autoview=sku
MSD Distributor 40* Timing
93 Octane Pump Gas

Am I leaving that much hp on the table with the 1 5/8 headers, increased bore/stroke and a little more cam? Which I could step up to 1.6 rr's.

 

We ended up with around 280 at .550 by the time we were done. Maybe I dont have enough cam.

I though about going to a 383 or 406 build with these heads. I even thought about a Procharger setup. I know these head would hold me back to a limit without stepping up to a larger runner, say a 210.

 

I can say that my previous combo ( with a hydraulic flat tappet cam/.458"/218* ) respopnded very well to an upgrade to Pro Magnum 1.6 rockers.
Although it was a different day /same track scenario ( although the days were similar in temp/humidity/etc) I picked up 2/10's with no other changes.
It seems to be a popular swap and results are almost always for the better.

 

Im running Crane Gold 1.5 RR's, but I might be able to get a good deal on a set of the 1.6 versions. My Heads really didnt flow much difference between .500 and .550 lift.

 

I would look to the 1.6's, I think it would benifit you some, but a little more duration would be better with a new cam.. The inc lift with 1.6's will help as well if not from .500 - .600 but hitting the midlifts earlier. Other things would be to mill heads to get you around 11.3ish, 1.75 headers would not hurt and maybe a victor intake over the RPM.. Depends what you want, you have a strong combo now, just not optimized.. Most of those will likely raise powerband some, which will help take advantage of the heads, then maybe a little more stall.. You could probably get that combo down to deeper 11's but with trade offs.
Anyone of those may make minimal difference, but all would probably make some. Can you go powersteering, electric water pump? I have been using a proform waterpump for years and love it! Pretty cheap unit and works well for me
If you dont already have one.

 

I was having this discussion just the other day regarding the extra lift and whether the heads flow any better beyond their peak.
What was mentioned was that with the additional lift you'll pass the sweet spot ( max cfm)twice in a cycle and be at that point longer rather than if you just approached max cfm and then moved away. I think the theory has some validity however some may argue.

 

I will consider the 1.6's if I can get a good deal on them.

The heads are already milled into the first angle on the valve seats. Just on the 30*.

I have thought about the Hooker 1 3/4 LT's. I have the Hedmans with dual 2.5" pipe and dynomax bullets that dump before the rear.

I compared the Victor Jr vs the RPM air gap. I was just trying to stay in the cams power range. I could go to a electric water pump and a S10 manual steering box, kinda went back and forth on that also.

The biggest thing is I want to keep it streetable. I want to be able to drive it to the track. Not that these things would keep me from driving it on the street.

Maybe I need to just be happy with what I have an let it eat. lol

 

At 12.1 seconds!
You HAVE to get that tenth and a half. Something to be said for an eleven second street car.

 

Its even closer than that. It was 12.01 was my best. 12.16 was my old best. Sooooo close.

 

87_TA, So are you running a manual steering box with the proform pump?

I am running a serpentine belt with a/c delete and no smog pump. My alternator is on the drivers side. I know the TA setups are different. How do you have your belt ran?

 

Head CFM rating plays a big part in HP. A naturally aspirated engine needs to suck in air through the intake ports. The amount of air it can suck in is mixed with fuel and makes power. The more air/fuel the engine can burn, the more power it can make. That's the theory behind every power adder. Pump in more air so you can add more fuel and make more power.

For a naturally aspirated engine, you can only rely on the suction power of the piston to pull in the available air. Cam grind plays a big part on just how efficient the engine can pull in the air but the heads are the limiting factor on the maximum amount of air that can be pulled through them.

Estimated Horsepower Based on CFM -
HP = .2575 x CFM (@ 28" of water) x number of cylinders

So those AFR heads peak out at 262 CFM. The maximum HP they'll produce is just under 540 flywheel HP. To achieve that number, the rest of the engine needs to be completely matched with camshaft, timing, fuel, compression etc. That number is just the maximum the heads will support, not what your engine actually makes. Now with a high end race engine that can achieve more than 100% volumetric efficiency, that number can actually increase.

Information about HP and torque
http://www.hardtail.com/techtips/hpexplained.html
http://www.hardtail.com/techtips/hpandtorque.html

 

With the work we done to the heads, we ended up with around 285 cfm. That in turn should support 570 hp if everything is working at 100% like you said. So if I building a 500 hp 383 or 406, then my heads shouldnt be the limiting factor. Now my build I have now seems to be matched fairly well, but im sure I could improve on it.

I guess I could do nothing but add a NX 150 shot and be in the deep 11's, but I like doing it NA. I would consider a Procharger, but I would just build a different motor in that case.

When it comes down to it, No im not using the heads to there full potential. So I should look elsewhere in my combo to improve mph.

Oh yeah, Thanks Stephen for the links and the formula. Im not as hardcore racer like you, IHI and Shagwell. My pockest are not as deep! lol
I have followed all three builds as well as some local racers and friends. I just want a strong running street/strip car that I can drive to the strip and still be able to go out for a milkshake or local cruise.

Im not worried about getting into the 10's, but im so close to 11's, why not just give it that extra nudge.

 

This should keep you busy for a while. A massive information page on heads of all sorts.

http://users.erols.com/srweiss/tablehdc.htm

If you read the explanation at the top, the first HP number is the generally accepted formula. The other 2 higher numbers are racing formula calculation results. You should never achieve those numbers unless you're running a Comp Eliminator or ProStock engine..

If you look for those AFR heads, you'll see the lower HP number is very close.

Using that page, the head swap I did over the winter should get me around 100 more HP. 100 HP in a low 9 second car isn't a huge drop in ET compared to a slower street type car.

 

was that with the T56, i dont remember you dyno'ing that car again with the manual. I would have thought you were closer to 475-500whp since you run as fast as my nitrous 383 just about, and i estimated 500-520whp for my nitrous shot.

3400 lbs and 112.5 trap speed is good for 330 whp or so. Most 3600lb LS1's run 111-112 with 340whp

 

Thanks for the link. I will have to check it out at home, Work has half the web locked down for some reason. lol

Yeah, I understand about adding 100hp to a faster car. My best friend runs a 72 Nova with a 408 that runs low 6.30's in the 1/8. He had a 388, we used the same heads on the 408. We opened the heads up some and added some compression. The numbers show he picked up 50 to 75 hp, but his et is about the same.

Were I am at with my car, it doesnt cost as much to pick up et/mph. But with your car and my buddys, it starts getting expensive just to pick up a tenth or a few hundredths.

 

True up to a point. An increase in the volumetric effeciency can be had with a well designed header/collector/ exhaust. There's more to it than just the piston drawing in the air.
Check out this article ( although I suspect you probably already have ). It applies to street driven vehicles as well.
http://www.superchevy.com/technical/...exh/index.html

 

Based on your 1/8th MPh you should have been trapping at 114.3MPH

Were you runnig into the wind that day?

 

thats a pretty cool calculation, i never even knew about it! thats saying my ported factory casting LT1 heads will support 597hp!

 

I put your combo in desktop dyno and it says you should have ~480 at the flywheel. Seems pretty accurate with everyone else's estimation.

 

Yeah, there could have been a head wind. I may be shifting too early also. The cam range tops out at 5800. I shift at 6k or 6100 and cross the 1/4 line at 6k. I think the 3.73 gears, th350 and 26" tall tires are matched fairly well with my intake and cam.

But yeah, I would love to trap 114's mph. That should put me in the 11.80's shouldnt it?

 

So I have some guys saying 475-480 at flywheel and some saying 375-385 at the flywheel. Which is it? I have seen people say 328-330 at the wheels.

At 375 flywheel - 20% = 300hp at the wheels.

At 425 flywheel - 20% = 340 hp at the wheels.

Unless my trap speed picks up, I doubt the mid to upper 400 hp range.
Now at the 375 to 425 hp range at the flywheel, I might beleive.

But thanks for running it through DD!