DownUnderIROC

I produced this graph of my 305 motor with "Dyno 2000" simulation software. You plug in detailed specs for the motor (including Tuned Port Injection), and out pops a dyno graph. I dont know how accurate it is, but I thought I would try it since my car has never been on a chassis dyno.
The simulation shows flywheel figures, and with my current setup it says the following:

Peak power = 338 HP @ 5000 and 5500 RPM (252 KW)

Peak torque = 385 FT/LBS @ 4000 RPM.

I have little / no experience with dynos. Can you give me some comments? Torque seems to drop off sharply after 5000 RPM, which is what I expected and felt with the stock Tuned Port Injection intake components.

What RPM would you shift at if you were dragging this car? Any other comments are welcome. Thanks.....



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1987 Chevy Camaro IROC-Z. 305 TPI. 700R4
14.6 secs @ 93 MPH.
2.14 sixty foot.
Nitrous soon! :-)
http://www.camaro-firebird.org
Camaro and Firebird pages in Sydney, Australia.

MrJ

Thats cool... those numbers same high though... WAY high. Judging by your trap speed you have closer to 200rwhp. Was that run made with all the mods you have now?

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91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter

Built on Wednesday

Joseph Andres

iTrader: (6)

Those numbers are most likely at the flywheel measurements. RWHP and RWTQ usually result in a 20% loss due to the drivetrain components.

Joe

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

DownUnderIROC

Yes the run was made with all the mods I have now, which can be seen at http://members.optushome.com.au/ozfb...m/jimmods.html

However I made that run in full street trim, with no special preparations. I drove to the track from work and raced.

Also, that run was in the middle of summer here. The temp was around 90 deg F, and humidity was very high. (Typical summers day in Sydney). I think I can shave at least a few tenths off that time in favourable weather conditions.

[This message has been edited by DownUnderIROC (edited April 30, 2001).]

[This message has been edited by DownUnderIROC (edited April 30, 2001).]

mulot30th

If you have 338HP and 385ft-lb of torque, then I'm asking myself how much that would give mine?



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1999 30th anniv. TransAm #877
** BESTS:60ft=1.935 1/4 ET=13.08 MPH=111.8 ** (Only 3.5K miles)
T-TOP,6M-Hurst,12cd, TCS
!EGR * !MAF Screen * ported and polished MAF * !silencer baffles * ! lid baffles * ported and polished TB * removed primary and secundary baffles * sealed ram-air * 9.4k timing-tricker * !CAGS * Mobil 1 * Lou's short stick * BMR panhard rod * BMR poly/poly LCAs * !DRL * Polished SLP resonator catback * 2 Ractive mufflers * 3x3 'fernco' mod * K&N * TB stop grind * Grotyohann headers * offroad Y-pipe* Power pedals * 19+ coats Zaino * WHITE gauges cluster * blue door TA badges * pontiac windshield decal * Polished momo shift **** * 4.5" brosal exhaust tips * Kenny Brown DD SFC
Ordered:
Polished: Calipers * Hood struts * Air tubes * Valve covers,Heat shields , etc.
Later:Cam + spring + pushrods swap + stage II heads
2000 Black Z-71 K1500 5.3l
ext.cab * !intake baffle * !MAF screen * !EGR mod

Jono

Dyno 2000 gives flywheel hp

Guest

I'd say those numbers are pretty optimistic. Probably reality is more like 260hp and 340tq looking at the time and speed in your sig. You can play with it a little to get it more accurate, but the HP and TQ peak are 500rpm too high for a typical TPI car. See if you cant get the tq peak at 3500 and hp peak at 4500 and it will be a bit more realistic.

90Iroc

He's running a 14.6. My 1990 Iroc with 305 TPI ran a 14.7 and was dynoed at 211 RWHP and 284 lbs. TQ. What percentage is usually assumed to be lost through the drivetrain?

DownUnderIROC

I agree that those numbers seem high. However I believe that I was accurate with the Dyno 2000 program in the data that I supplied.

305 ci Chevy
Tuned Port Injection (600cfm @ 1.5in/hg)
Crane 2031 HR
Low perf heads, pocket ported.
etc.

I plugged in the exact mods that I have on my IROC.

Tim Burgess

Jim, unfortunately, Desktop Dyno 2000 does not allow the (long) runner length to be factored in to the simulation, so the results will be more along the lines of what a Mini Ram would produce at the upper RPM range, according to TPIS.

Tim

RCR

I'd like to add that iff you used the roller cam option, it adds to the inflated value. The manual states to use roller for race type cams, otherwise use the lesser profile. (I have the program at work otherwise I'd tell you which one to use.)

Mark 89Formula

Tim and RCR are on the money. Make sure you select "Hydraulic flat tappet lifters" rather than "Roller Solid or Hydraulic lifters". The "Low Performance Pocket Ported" head option WAY overstates the airflow potential of a mildly worked LB9 or L98 iron head. Also make sure you set the intake valve size to 1.84" rather than 1.94" unless you've installed oversize valves.

I agree with Madmax on what your #s should look like. My results for a mildly modded 89 L98 are 264 HP @ 4000 RPM and 382 ft-lbs torque @ 2000 RPM FWIW.

DownUnderIROC

Thanks for the ideas guys

The program just "appeared" in my email one day, so I dont have any kind of User Manual for it.

Tim, if you look at the torque curve I think that the TPI intake may be factored in? Especially on the new graph I have produced.

Mark, I kept the "low perf / pocket ported" heads because I feel that is an accurate description of what I have on my motor. You are saying that the flow numbers are too high?

I changed the cam to hyd flat tappet (even though it is a HR), and changed the camshaft duration to specs @ 0.050 lift, instead of advertised duration. This gave me the following (more realistic?) result:

308 HP @ 5,500

349 FT/LBS @ 4,000

Remember these are flywheel figures, not RW.

------------------
1987 Chevy Camaro IROC-Z. 305 TPI. 700R4
14.6 secs @ 93 MPH.
2.14 sixty foot.
Nitrous soon! :-)
http://www.camaro-firebird.org
Camaro and Firebird pages in Sydney, Australia.

[This message has been edited by DownUnderIROC (edited July 16, 2001).]

[This message has been edited by DownUnderIROC (edited July 16, 2001).]

import'sdread

There was a car(60's Camaro?)in an issue of Car Craft that made 290 RWH on the dyno. It ran 11's! They also tested a fourth gen that made more RWH stock, and it ran 13's. How can this be?

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1989 Trans Am, 305 TPI 5-speed, T-Tops(love 'em),4-wheel disc, 3.73 posi. '97 Camaro V-6 T-Tops

Mark 89Formula

Jim, if you look in the air flow file for the pocket ported heads you'll find the values are identical to the "ported, large valve" selection (at least in my version of Dyno 2000). In any case there's no way a small valve iron 305 head will flow 239 cfm @ .500 lift with a depression of 25 in-H20 unless it's been FULLY ported (and I still have my doubts).

I ran your combo with stock L98 iron heads and came up with 262 HP @ 4500 RPM and 339 ft-lbs torque @ 2500 RPM. With AL L98s it simmed at 281 HP @ 5000 RPM and 347 ft-lbs @ 3500 RPM due to the superior exhaust port of the AL head. That's the ballpark you could be in given a good tune.

DownUnderIROC

Well Mark I actually had my car dynoed and you were 2 HP off!

On a Dyno Dynamics dyno, my car posted 130KW at the rears. This converts to 260 HP at the motor. The other graph below is with a 50 shot of Compucar nitrous, and that comes out to 310 HP at the motor.

Seems like that dyno simulation is deadly accurate if you use it right. BTW my car went 13.62 secs @ 102 MPH with the 50 shot, on street tyres and in full street trim.






[This message has been edited by DownUnderIROC (edited July 16, 2001).]

DownUnderIROC

Here is my car on the dyno.....