Another RSR Clone Project - Dyno Day

[KTL]

Very similar to Chris Streit's engine. Maybe he'll chime in a bit. I've seen his car go. It GOES. And has kept going for 3 race seasons now. And he drives the snot out of it every time out. As evidenced by his success. GT-2 champ once again.

One difference that jumps out at me is Chris uses Electromotive crank-fire twin plug.

[randywebb]

Fabulous work!

re Single MSD driving two coils - see comments from Steve Wiener re my setup like this -- you may want to buy another box...

[Purkinjefibre]

Beautiful motor,

question, why stop at 7500rpm? what is the limit?

cheers
Brett

[RoninLB]

Originally posted by tom1394racing
Torque is between 165 and 180 ft-lbs from 4000 to 7000 RPM. Accounting for driveline loss equates to 190-207 ft-lbs from the engine. The muffler causes a loss of 20 ft-lbs across the rev range consistent with the 20 HP loss.

Originally posted by Superman
it makes about the same torque as my engine, which is mostly stock. I don't have my dyno sheets in front of me, but I recall it made about 205 lb/ft assuming a 15% drivetrain loss.

Originally posted by Superman My torque curve looks like my kitchen table. It goes to about 90% power around 3000 or 3500, with good power below that, and peak power remains until about 500 rpm, where it begins to trail off, but not much.

Originally posted by camgrinder
Here is a very good explanation of HP and Torque:
Hp vs. Torque

From the author 2x
"What this all boils down to is, as far as maximum automobile acceleration is concerned, all that really matters is the maximum torque imparted to the ground by the tires (assuming adequate traction)."
"It's the torque applied by the tires to the ground that actually accelerates a car, not the torque generated by the engine."

----- So if I understand all this correctly then if Tom's & Super's car both started in the same gear and speed at 3.5k, and pulled to 6k, then they should be about equal.

That means those carbs need tuning. We confirmed this based on A/F?

How much torque is left on the table? It's gotta be a noticable amount? Tom's running the GE-60 cams in a 3.0 which is more cam than the 3.0 RSR cam. It better be really noticable or Tom will have to work at beating Super's engine.

my little carb brain says Tom has some serious action still left on the table IF his carbs are really dialed in. And If 46-IDA aren't too big?

Originally posted by kepperly
I would make sure you are starting with the correct ID venturi, which on a 3.0ltr in the state of tune as yours would be around 38mm, in a set of of weber 40 ida-3c carbs. there are sets of venturi tubes avaiable for 46 IDA webers with 38mm ID for even more latitude in tuning.

Originally posted by RoninLB
carbs is carbs. The game is to atomize the fuel mix as much as possible. Just dumping in more fuel doesn't do any good if it can't be atomized.
btw.. it's a carb eat MFI world imo.

i gotta hear this engine..

[DW SD]

Originally posted by RoninLB



i gotta hear this engine.. [/B]

Ron, I know off topic, but where does the Carrera 3.2L 84 to 89 cam specs fit into this chart?

[camgrinder]

Toms car after 5k would pull away from supers. Super would have to shift and lower the multiplied torque to the rear wheels. That is if they both have the same gearing and tire sizes.
Toms engine is designed to be run from 4500 to 7500 rpms.
Supers engine is probably happy from 2500 to 6000. Hopefully both are geared correctly to take advantage of thier powerbands.

The DC60 (Ge60) has less duration than the 3.0 RSR cam and a much lower powerband.

The specs listed in BA's book for the L cams are incorrect. The L has the same cam specs as a E cam.

The 3.2 Carrera cams have the same specs as the 3.0 Sc , they are timed different in the engine.

[RoninLB]

Originally posted by DW SD
Ron, I know off topic, but where does the Carrera 3.2L 84 to 89 cam specs fit into this chart?

Wayne didn't have lift #'s in his Engine book for the '84-89. Neither did Bentley. That's all I have.

[tom1394racing]

Wow...I didn't think my dyno results would generate this much discussion.

I am running 46mm PMO's set up as follows:

AV's 4.5
Vens 4.0
Mains 160
Idles 55
Idle Airs 180
Tubes F16
FBCV's 50

Scott at Auto Associates and I discussed the AFR results and decided not to make any changes in the carbs, Here's why:

The dyno runs started at 3500 RPM so the data below 4000 rpm is not real. Most of the time I will be running the car with the muffler capped and the car running rich (between 11.5-13 AFR). This will be true on the street and at many of the racks I expect to run where noise is an issue. When I am able to run without caps, It will be on the track where the engine will be operating between 4500 and my 7500 RPM shift point (I have a short gear stack in the tranny). If we were to richen up the carbs, we would end up with an AFR at 11 or below with the muffler capped. This would give away too much power.

Someone asked about achieving the 10.5:1 CR with the Mahle RSR P&C's. I'm running early SC heads that have been machined for twin plug and to give 84 cc chamber volume. With that and a deck ht of 1.2 mm, I measured 10.5:1 CR. I'm told that this is a pretty standard set-up for a high performance 3.0 liter.

There was also a question about single vs dual MSD for twin plug application. Auto Associates recommended the single set-up. They build all of their twin plug motors that way and have spoken with MSD who concur with them. I'm told that Jerry Woods also uses the single MSD in his applications.

The muffler is really trick. It is a replica of a factory ralley silencer. There is a pic on page 138 of Bruce Anderson's 911 Perf Handbook vol 1. The discharge pipes line up with the megaphone inlets from the headers so when the caps are off it acts like open megaphones. With the caps on it dischages to a downward pointing exhaust hidden behind the rear valence. I'll post some pics when I get a chancce.

[dean]

Another thing that might be a problem with a comparo of the two motors is the dynos that were used.

I am guessing that Superman used a Dynojet and we know Tom used a Dynapack. The Dynojet is much more optimistic with the #'s than the more conservitive Dynapack. So it is hard to compare different dynos.

Dean

[JohnJL]

Excellent job Tom!
I am anxious to get mine out to the dyno now, as we started with the same base engine but ended up making different choices along the way:
3.0 SC
11.5:1 JE Pistons
Carrera intake megasquirted
Heads ported and smoothed (but not polished)
Boat-tailed mains
Twin plugs EDIS
DR20 cams
Bursch headers
Flowmaster 2-into-2

If I knew now when I ordered them I probably would have gone with a more aggressive cam but lets see...

again, congrats

[tom1394racing]

Just spent the weekend running DE at Watkins Glen. We were able to run caps off on the muffler. The car made great power and sounded outrageous.

Keep us [posted on your dyno results.

[911teo]

Hey Tom how about your engine temps? What did they run into?

Thanks!

[Mr Beau]

I've noticed at the top of the graphs it states "Fly Wheel Horsepower". Is there some correction factor (15%?) already being used to give these numbers?

[jorian]

Tom,

Love the car. Sorry, longish question.

Why did you go with the 46mm PMO's rather then 40mm. I've heard that 40's are perfect for 3.0 & 3.2 liter set-ups, and 46mm are best suited for 3.4+ motors. The reason I ask is I just picked up a 3.0 litre SC with euro heads and 46mm webers. The motor seems a little sleepy below 4500 rpm but loves 5-6000. I guess you can always downsize by running smaller venturis but there must be some downside to this as well.

[kenikh]

If he's running to 7800 RPM, that motor needs the 46mm carbs to get enough air into it.

[tom1394racing]

The HP numbers on the dyno charts are rear wheel HP and torque. A 15% correction still needs to be applied.

My son and I ran the car in back to back sessions at the Glen last weekend. After 40 minutes of hard running the oil temps were still below 210 deg F.

The motor needs 46 mmm carbs. The GE 60 cams combined with the big port heads, 1 3/4" headers and the 7500 rpm rev limit require lots of air and fuel. We used almost 17 gallons of race gas in 6 20 minute lapping sessions.

[jacko241]

What kind of lap times were you running?

[jorian]

Thanks for the info Tom.

[tom1394racing]

Originally posted by jacko241
What kind of lap times were you running?

We're still learning the car.

I was the 2nd fastest car in the yellow run group. I was turning around 2:28 minute laps. I was braking way too hard gong into each high speed corner and was not carrying enough momentum into the turns.

Still learning!!

[jacko241]

Ok, thanks Tom. Was just curious, as my brother ran the HSR race there a few weeks ago.