Are there differences between the two? What would the theory be for a good road race tune and what would the theory be for a good drag race tune?

Specifics on how to tune boost, fuel and timing. Lets hear it.
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Hehe, this could get fun. I hadn't thought of it but here are some of my ideas.

Drag race Tune: In a drag race engine longevity isn't too much of a concern since you are only running it for about 13 seconds depending on the car. So I would run as much timing and the leanest air fuel ratios possible that don't knock, my target EGTs would be much higher since the car would only spend a short period of time at full load. Boost you would want to come on as fast as possible and hold at its maximum.

Road Race Tune: Here, you are running the engine at full load for much longer times. My tune for this would run much richer AFRs to combat knock and timing would be more conservative than the drag race tune. For boost you would want it to come up fast but not running at the turbo's limit all the time. Road race is sort of like an endurance, you shouldn't push the engine to its absolute limits for speed. Instead trade some of that time for handling.
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Would more load sites be dedicated to high load on a road race tune? Does it matter? I guess this could apply to fueling, iginition and boost control. I wonder if professional tuners scale differently depending on the application.

Lets hear more theories and opinions.. =)
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Road-race: Smoothness and driveability as much/more important than outright power. Will not tolerate ballistic boost onset, and you definitely need to focus on the WHOLE map (not just high load/WOT). You need to be able to adjust the car's attitude with subtle changes in throttle, having boost chasing itself and coming on hard is NFG (ask anyone who's driven an old 911 turbo)

Drag: Max power and fastest boost onset as possible. Can definitely bias towards higher EGT's and leaner AFR's due to the limited time at temp. Also, you could play games with the part-load points to get the turbo spooled up at launch/part throttle and not care about loss in torque.
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The other thing to look at would be target boost control in certain gears. For dragracing, I would probably set the wgdc in either 2nd or 3rd gear and allow for the car to boost spike in 4th. For road racing, I'd want to set the wgdc for 4th gear. This would be for a 5-speed, btw.
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The other thing to look at would be target boost control in certain gears. For dragracing, I would probably set the wgdc in either 2nd or 3rd gear and allow for the car to boost spike in 4th. For road racing, I'd want to set the wgdc for 4th gear. This would be for a 5-speed, btw.
Right on the money, this is what I do.
I set WGDC in 2nd.
Actually, I don't do much to set it at all. I let the wg comp tables(played with them for quite a bit) take care of it, not the max WGDC table.
Since I'm on the stock boost control, it works pretty well. I don't get any spiking unless I mash it at 2500-3000 in 5th. Then it will spike to about 25psi(target is 22). SO I just avoid doing this on the street. It is more effective to downshift anyway.
The rest of the time the boost curve is great, if a bit abrupt.
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if you are talking about the same hardware/parts there is no difference

want the same things out of both until you start talking about nonstreetable drag cars
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Same parts. I was wondering if you'd tune a car differently if you want the best drag times or the best road race reliablility. The above posts show one example. You'd want as much boost as possible in the power gears and you don't mind boost control as much for the top gears. I wonder how much difference this would make.
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Same parts. I was wondering if you'd tune a car differently if you want the best drag times or the best road race reliablility. The above posts show one example. You'd want as much boost as possible in the power gears and you don't mind boost control as much for the top gears. I wonder how much difference this would make.
Pretty noticeable difference.
Also for drag racing, you wouldn't worry about EGT's as much. I consider a drag tune and a street tune to be similar in this respect. It least for me.
I don't do sustained high speed runs or highway roll racing (real racers run from a dig :devil: ). I can count the times I've been full throttle in 5th on one hand and have fingers left over.
EGT's are not as high of a concern to me.
That means I can run leaner AFR's.
I would tune the car differently if I was going to go road racing, depending on how it responded and how hot if got on long pulls. Not a lot of time for the EGT's to drop back off on a road course.

If you are tuning for someone besides yourself, it's a whole different thing though.
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On the drive by wire cars if you are reflashing, you can also make the throttle pedal more like an on/off switch so it opens faster. Probably not that big of a deal, but every little bit helps. You might also cut timing at high RPM and low to mid-low loads.
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I'm the other way around. I try not to beat on the car from a stop to preserve the clutch and tranny. I run afrs in the upper mid 10s (10.8-10.7) after 5600 rpm and run very conservative timing but tend to hold boost for longer than some people like to. I see manye VF39 tunes that drop in to the 13psi range at redline. I'm running a 16g and I am running 16psi at redline. Different turbos though. I tried advancing timing up top to bring EGTs down but the car didn't like it. I usually see EGTs about 1620F on 4th gear and partial 5th gear pulls. I'm looking to bring the EGTs down in the the mid 1500 range.

For a road race machine.. safer to run more boost and less timing or less boost and more timing?

As for the DBW TDC tuning. Tuning the TDC table works wonders for the feel of the car. Not sure how much difference it would make on a drag car but on a road car it could help the feel of the car.




Pretty noticeable difference.
Also for drag racing, you wouldn't worry about EGT's as much. I consider a drag tune and a street tune to be similar in this respect. It least for me.
I don't do sustained high speed runs or highway roll racing (real racers run from a dig :devil: ). I can count the times I've been full throttle in 5th on one hand and have fingers left over.
EGT's are not as high of a concern to me.
That means I can run leaner AFR's.
I would tune the car differently if I was going to go road racing, depending on how it responded and how hot if got on long pulls. Not a lot of time for the EGT's to drop back off on a road course.

If you are tuning for someone besides yourself, it's a whole different thing though.
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For a road race machine.. safer to run more boost and less timing or less boost and more timing?

I don't think I would say it that way. Not necessarily less boost. I would try to stay closer to the more efficient ranges of the turbo I was running to keep heat down. The tune timing after I was done with boost.
I have never been road racing, so I have no real experience with it.
That is just where I would start if I was going to tune my car for such use (hard use measured in minutes and not seconds).
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What happens when your road race is so long that it will require refueling? Make a really conservative/rich map and then you have to pit in one or two more times. Then you lose the race. :( How lean would you go?
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with roadrace tunes use lower boost levels to prevent overheating of the turbo.you dont want to go to rich.high 10"s are good.adjusting knock correction tables would need to be done.

dave
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What kind of fuel are we talking about here? 116 vs 93 octane will significantly change the way you would calibrate the ECU.
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93 oct..

What kind of fuel are we talking about here? 116 vs 93 octane will significantly change the way you would calibrate the ECU.
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Hehe, this could get fun. I hadn't thought of it but here are some of my ideas.

Drag race Tune: In a drag race engine longevity isn't too much of a concern since you are only running it for about 13 seconds depending on the car. So I would run as much timing and the leanest air fuel ratios possible that don't knock, my target EGTs would be much higher since the car would only spend a short period of time at full load. Boost you would want to come on as fast as possible and hold at its maximum.

Road Race Tune: Here, you are running the engine at full load for much longer times. My tune for this would run much richer AFRs to combat knock and timing would be more conservative than the drag race tune. For boost you would want it to come up fast but not running at the turbo's limit all the time. Road race is sort of like an endurance, you shouldn't push the engine to its absolute limits for speed. Instead trade some of that time for handling.


Very well put...

If I was tuning for drag racing, it would be tuned on the edge, shooting for the highest torque all over the power range the engine sees during the run...
Anti lag would also be tuned into it as well...

Road racing tunes need to have a smooth/wide torque curve to keep it driveable, and must be very reliable in every weather/track condition...
Things like fuel consumption, drafting effects on the cooling system, and heat soak have to incorporated into the tuning as well....

I would approach the tunes completely differently...
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