My Doug Levin Motorsports Dyno SHeet!
- Thread starter Dr Roof
- Start date
Gerald
Enthusiast
Nice David, don't you have a stock bottom end and stock cam? 840+RWTQ at 3,500 RPMS??? That's serious!
I need to get my dang car back to Doug..
Gerald
I need to get my dang car back to Doug..
Gerald
MichaelP
Enthusiast
Yea well I have 400 RWTQ at 5800 RPMS.
WOW that must be nice.
Paolo Castellano
Enthusiast
David, nice dyno sheet! No wonder you went 142 MPH in the 1/4!
Dr Roof
Enthusiast
Gerald
The bottom end is stock and these numbers are with Pump Gas!
The bottom end is stock and these numbers are with Pump Gas!
cstegall
Enthusiast
David,
I am salivating here ....awesome numbers
CStegall
I am salivating here
....awesome numbers CStegall
Dr Roof
Enthusiast
Clark
You will soon experience the joy of these cars
You will soon experience the joy of these cars
Larry Macedo
Enthusiast
Very impressive @ 11:1, David! Congrats.
Torquemonster
Enthusiast
Wow David - leaning it out from 11:1 to 12.7:1 would definitely net even more power. Given the conservative fuel curve I'd guess the timing had more left in it as well. That's right up there for a conservtaive tune!
David,
I guess Red_Dragon needs to reconsider his offer on racing a Viper. The little kid seems to be full of himself with his poopra.
I guess Red_Dragon needs to reconsider his offer on racing a Viper. The little kid seems to be full of himself with his poopra.
Dr Roof
Enthusiast
Ab
I figure me and you can hook up one night and take care of business with him.
I figure me and you can hook up one night and take care of business with him.
TurboRob
Enthusiast
Actually, 12.7:1 A/F on the dyno would more than likely scatter the engine on the track. We tune all FI cars to between 11.0:1 and 11.5:1 on a dynojet. With the efficiency of the intercooler at speed, actual A/F will lean out to about 12.0-12.5:1 on the track. This is also one of the reasons that many turbo and supercharged intercooled cars seem to be so much faster at the track than the dyno sheets would lead you to believe. It has been my experience that when using an efficient intercooler, track mph tends to show an additional 3-5% HP over the Dynojet numbers. Which is rarely ever the case with NA engines.
In example, I run my turbo Buick very conservative at 10.2:1 on the dyno. But at the track, the same tuning yields 11.0:1 on the datalogger.
Keep in mind, David dynoed on PUMP gas. I'd be nervous at anything over 11.5:1 with 93 octane. But that's just me.
Nice numbers David. If you stop by tomorrow, we'll post your new dyno sheets.
Torquemonster
Enthusiast
TurboRob - thanks heaps for sharing that insight - I never knew that a boosted engine leaned out on the track compared to a dyno pull.... that is very valuable information... most of my fine tuning has been on a track not on a dyno - maybe that's why I've tended to be less conservative with A/F ratios and got away with it.
I don't like dyno's much - it seems a waste of good engine other than doing analyser work - when with laptops etc it can all be done on a track and in real world conditions. I know for some things a dyno is simply the most practical tuning device... but the track always tells the truth impartially The car goes quicker between test points - or it doesn't.
I don't like dyno's much - it seems a waste of good engine other than doing analyser work - when with laptops etc it can all be done on a track and in real world conditions. I know for some things a dyno is simply the most practical tuning device... but the track always tells the truth impartially
The car goes quicker between test points - or it doesn't.Mike Brunton
Enthusiast
Max,
The reason for the difference is that Roofs and Mash's car are NOT running the same amount of boost. When you boost an engine, you effectively increase displacement. Roof's car is running 33% more boost (+4psi) than Mash's car, as I understand.
Ben Treynor stated in another thread about a pretty linear 28hp per PSI increase - so I guess the question could be "why is Roof's car not making alot more HP than Mash's car with 33% more boost?". The answer would be the displacement difference.
Everyone likes to say how "power under the curve" is the most important thing - and that's true - BUT ONLY FOR THE RPM RANGE YOU RUN IN!
You top out in 1st, then shift into 2nd at, say 5,900RPM (just pulling numbers from the air), and when you get into 2nd, you're at 4,900RPM. Well, what matters MOST then for best speed is the area under the curve from 4,900 to 5,900RPM. And actually, from comparing the two graphs, it appears that the Heffner car is making about the same power from 4,500 to 5,000 with the edge going to the DLM car... 5,000-5,500 is very close - there is a dip in the Heffner graph (wonder why? anyone?) but it looks like the "area under the curve" is just about equal. From 5,500-6,000, it looks like the Heffner car makes ALOT more HP and a fair bit more TQ in that range than the DLM car.
The "area under the curve" is important below 4,000 only when you're trying to show your buddies how fast your car is and putting around town looking cool but in the real world and in a race it means virtually nothing. All IMO, though.
I'd love to see a race between Mash and Roof. I think, all things being equal, the DLM car would pull in the lower end of the gear, and the Heffner car would pull harder in the higher part of the gear.
Mike, thanks for taking the time to explain the difference. i was comparing the two dyno charts and thought the principal of a stroker motor would be to make more torque then the stock stroke, stock cam engine ???
Wouldnt a bigger cammed, bigger engine show less boost but make more power? i thought bigger cams and bigger engines show less boost but make more power because they flow bettr. i really didnt mean to start a flame war on the other thread but i honestly dont understand why to build a stroker engine and make less TQ? i cant say i agree with you about not needing the tq under 4000 rpm, the nitros guys have it instantaneously and theyre getting at the end of the track quicker.
thanks again
Max
???Wouldnt a bigger cammed, bigger engine show less boost but make more power? i thought bigger cams and bigger engines show less boost but make more power because they flow bettr. i really didnt mean to start a flame war on the other thread but i honestly dont understand why to build a stroker engine and make less TQ? i cant say i agree with you about not needing the tq under 4000 rpm, the nitros guys have it instantaneously and theyre getting at the end of the track quicker.
thanks again
Max
Mike Brunton
Enthusiast
Max,
I'm definitely not an expert when it comes to this, but a stroker motor is almost always NOT "good" with forced induction. As for the cam, it's been a while since I read Corky Bell's book but I do recall that a "big cam" with alot of overlap is pretty much the opposite of what a supercharger needs. A supercharger is ramming the fuel and air into the engine, and the higher cylinder pressure is forcing it out, so you don't need as "big" of a cam to try and get every last drop of restriction out, you can let the supercharger push it in.
As for "why build a stroker and make less"... between you and me (and everyone else reading this thread), what I heard was that Mash sent his car to Apex to get the lethal, and at the last minute told them he was getting it supercharged too. I heard he wasn't aware that a stroker motor + SC are sort of opposites in many ways, and had figured that a big engine + a big SC would be a big big result, but Heffner clued him in at the last minute and Apex 'adjusted' the package to be SC-compatible. Maybe I am wrong about that - just what I heard. You make a good point though - there really ISN'T any reason to stroke the motor and then supercharge it, IMO. That is why this 550cid motor doesn't make the torque you may expect. On the other hand, that big motor is why he's making (approximately) the same power as Roof's car with alot less boost.
As for the NOS guys and TQ, you are running through 1st, 2nd, 3rd, and part of 4th (or all of 4th if the car's got gears). 25% of your time is spent in 1st. Of that, you launch at probably 2,000RPM, and shift a bit before 6,000RPM. Between 2kRPM and 6kRPM is a 4kRPM range... the 2-4kRPM area is 50% of that range.
So, if you make a car have a lot of low-end grunt, you're spending alot of time making it faster in an RPM range that is only going to be seen for less than 13% of your 1/4 mile run. Better to optimize the 4-6kRPM area where you will spend 87% of you time. Optimizing the <4kRPM area is going to make the car "feel fast" around town, because off the track, I bet 95% of the driving is below 4kRPM's.
As for NOS, the thing with NOS is it gives you alot more TQ because it flattens out your TQ curve. That's why those guys can dyno >900LB-ft but only ~700HP. I think the reason the NOS guys are going so fast is they've gotten real good at progressively controlling the NOS and kicking it in when they can use it, instead of sitting on the line spinning. Also, I think all the really fast 9-second Vipers have a fair amount of motor work - at least heads+cam, if not more. They can tune the motor for NOS and squeeze the most out of it. But they can't change physics - the RPM range they run in is dictated by the gearing (rear end and transmission), so whatever they get in the RPM range the use is what is making them fast... I bet those guys don't drop below 4.5kRPM on any of their runs after they are out of 1st!
I'm definitely not an expert when it comes to this, but a stroker motor is almost always NOT "good" with forced induction. As for the cam, it's been a while since I read Corky Bell's book but I do recall that a "big cam" with alot of overlap is pretty much the opposite of what a supercharger needs. A supercharger is ramming the fuel and air into the engine, and the higher cylinder pressure is forcing it out, so you don't need as "big" of a cam to try and get every last drop of restriction out, you can let the supercharger push it in.
As for "why build a stroker and make less"... between you and me (and everyone else reading this thread), what I heard was that Mash sent his car to Apex to get the lethal, and at the last minute told them he was getting it supercharged too. I heard he wasn't aware that a stroker motor + SC are sort of opposites in many ways, and had figured that a big engine + a big SC would be a big big result, but Heffner clued him in at the last minute and Apex 'adjusted' the package to be SC-compatible. Maybe I am wrong about that - just what I heard. You make a good point though - there really ISN'T any reason to stroke the motor and then supercharge it, IMO. That is why this 550cid motor doesn't make the torque you may expect. On the other hand, that big motor is why he's making (approximately) the same power as Roof's car with alot less boost.
As for the NOS guys and TQ, you are running through 1st, 2nd, 3rd, and part of 4th (or all of 4th if the car's got gears). 25% of your time is spent in 1st. Of that, you launch at probably 2,000RPM, and shift a bit before 6,000RPM. Between 2kRPM and 6kRPM is a 4kRPM range... the 2-4kRPM area is 50% of that range.
So, if you make a car have a lot of low-end grunt, you're spending alot of time making it faster in an RPM range that is only going to be seen for less than 13% of your 1/4 mile run. Better to optimize the 4-6kRPM area where you will spend 87% of you time. Optimizing the <4kRPM area is going to make the car "feel fast" around town, because off the track, I bet 95% of the driving is below 4kRPM's.
As for NOS, the thing with NOS is it gives you alot more TQ because it flattens out your TQ curve. That's why those guys can dyno >900LB-ft but only ~700HP. I think the reason the NOS guys are going so fast is they've gotten real good at progressively controlling the NOS and kicking it in when they can use it, instead of sitting on the line spinning. Also, I think all the really fast 9-second Vipers have a fair amount of motor work - at least heads+cam, if not more. They can tune the motor for NOS and squeeze the most out of it. But they can't change physics - the RPM range they run in is dictated by the gearing (rear end and transmission), so whatever they get in the RPM range the use is what is making them fast... I bet those guys don't drop below 4.5kRPM on any of their runs after they are out of 1st!
Torquemonster
Enthusiast
What an excellent and intelligent post Mike!
I agree - stroker needs are different... not sure I agree that stroker engines are not good for boost though - they can be excellent! The things to watch are block stability, rod ratio, and as you pointed out - cam needs are different.
Few have the time/money and determination to experiment with custom cams/head combo to get it right for just one engine - and to achieve full potential on a one off motor would be a tall order... I think the end result was very good for a one off.
if demand was high enough for that 550c.i. combo plus blower - Wayne or someone would develop a cam just for it, and it would make a big difference to the results! In the meantime - it's not bad is it?
I agree - stroker needs are different... not sure I agree that stroker engines are not good for boost though - they can be excellent! The things to watch are block stability, rod ratio, and as you pointed out - cam needs are different.
Few have the time/money and determination to experiment with custom cams/head combo to get it right for just one engine - and to achieve full potential on a one off motor would be a tall order... I think the end result was very good for a one off.
if demand was high enough for that 550c.i. combo plus blower - Wayne or someone would develop a cam just for it, and it would make a big difference to the results! In the meantime - it's not bad is it?
Mike Brunton
Enthusiast
I agree with you Torquemonster, I don't think strokers are bad for boost, per se, but if I had $38k to drop on my engine before getting it boosted, stroking it would be the last thing I would do. I'd bore it out, lower the compression (a bunch), put a very mild cam in, and make the rotating and oiling top notch before I'd spend a dime stroking it. Just my .02. But I bet for the same $$, I would end up with a faster machine than the guy who stroked to 550 and boosted it.
TomMiriViper
Enthusiast
Mike,
Excellent information. I was wondering about the same 550 ci engine and didn't want to upset the others with thin skin . Everybody got so insulted so I didn't want to stir the *** anymore. It was my belief to make a smaller engine perform like a bigger one is to turn up the boost and eliminate the need to stroke? That's what boost is all about .
Honestly, I don't want to insult anyone but I thought Dr. Roofs DLM built car makes impressive power for the stock cam and stock bore. I don't believe the boost number on the gauge really accounts for much as the stroker engine will show less boost because it flows more efficiently.
Tom
Excellent information. I was wondering about the same 550 ci engine and didn't want to upset the others with thin skin
. Everybody got so insulted so I didn't want to stir the *** anymore. It was my belief to make a smaller engine perform like a bigger one is to turn up the boost and eliminate the need to stroke? That's what boost is all about . Honestly, I don't want to insult anyone but I thought Dr. Roofs DLM built car makes impressive power for the stock cam and stock bore. I don't believe the boost number on the gauge really accounts for much as the stroker engine will show less boost because it flows more efficiently.
Tom
well said!!!Mike,
Excellent information. I was wondering about the same 550 ci engine and didn't want to upset the others with thin skin
Honestly, I don't want to insult anyone but I thought Dr. Roofs DLM built car makes impressive power for the stock cam and stock bore. I don't believe the boost number on the gauge really accounts for much as the stroker engine will show less boost because it flows more efficiently.
Tom
thanks Tom and Mike
Max
