Rev limit...WOT

[Illss1]

I had an issue posted here an i got my answer BUT had a concern about a thread i read on another forum about a guy having the same issue i had and that was bouncing off rev limter at wot from 1-2 (if need to be i can dig it up) and a few posters said raising the rev limit past 65-6600 will be dangerous for the SRT8 because of valve spring floating or some term like that and thats risking ur motor........ In that thread DIABLO suggested the same thing i got suggested an that was raise rev limit 2-300 . I believe i'm doing everything correctly and that is raising shift points and then raising REV limit in DRIVE 2-300 to eliminate the issue right ? Not touching REV limit in neutral at all leaving at CANNED specs right ? Are we SRT8 owners at risk with the high rpm wot settings we are getting told to set it at even though we have stock valve springs ?

[mikel]

Basically if you're not comfortable spinning it that high, dont use the raised shift points, or look into some valvetrain upgrades.

Thanks

[Illss1]

Basically if you're not comfortable spinning it that high, dont use the raised shift points, or look into some valvetrain upgrades.

Thanks

I'm fine with SPINNING it that high if ur saying 2-300 rpms is SAFE .....i mean if its safe then fine BUT if ur saying WE got a 50/50 chance of damaging something with stock valvetrain then i wouldnt expect the repeated answer of raise it 2-300 when this issue is brought up .

[dpotter]

I think you guys may be confusing some terms here. The rev limiter is a safety. I currently have mine at 6750, just cause I don't want it in the way with my shifts. Your car will only rev to the point of where you SHIFT at. So if you raise your shift points to say 6500, that's all the engine will see. You could have your rev limiter set to 12,000 and it wouldn't affect anything.

BTW, I ran 12.80's at the track last weekend with the raised shift points. No issues whatsoever.

[Illss1]

I think you guys may be confusing some terms here. The rev limiter is a safety. I currently have mine at 6750, just cause I don't want it in the way with my shifts. Your car will only rev to the point of where you SHIFT at. So if you raise your shift points to say 6500, that's all the engine will see. You could have your rev limiter set to 12,000 and it wouldn't affect anything.

BTW, I ran 12.80's at the track last weekend with the raised shift points. No issues whatsoever.

Ur saying that what i'm thinking of is shift points rpms an not rev limiter ? Maybe, but i thought once u raise shift points an raise REV limiter in drive feature that whatever ur set at say (6800) that thats what ur limit is ? I guess i'm not understanding smt ......

[SRT8Tech]

DO a datalog on it and see where it is shifting. Then start experimenting with the Predator and see what happens. I have mine set with the raised shift points and +200 on the rev limitter. It shifts right at 6400 give or take about 30-40 rpms either way. It wont hurt the car.

[Quick]

I think you guys may be confusing some terms here. The rev limiter is a safety. I currently have mine at 6750, just cause I don't want it in the way with my shifts. Your car will only rev to the point of where you SHIFT at. So if you raise your shift points to say 6500, that's all the engine will see. You could have your rev limiter set to 12,000 and it wouldn't affect anything.

BTW, I ran 12.80's at the track last weekend with the raised shift points. No issues whatsoever.

Ur saying that what i'm thinking of is shift points rpms an not rev limiter ? Maybe, but i thought once u raise shift points an raise REV limiter in drive feature that whatever ur set at say (6800) that thats what ur limit is ? I guess i'm not understanding smt ......

I think Illss1 is saying that he set his rev limiter quite high because he doesn't ever plan on hitting it since the car will shift before it gets there. More than likely true in his case. Note that the predator will allow you to disable the automatic upshift feature in auto stick mode. If you disable the automatic upshift and put the car in auto stick mode it will hold the current gear until manually upshifted. In this configuration the car WILL rev until hitting the rev limiter. I do not have my automatic upshift disabled. First of all I'm just not good enough to beat the automatic upshift and second I do occassionally bump the shifter and inadvertently drop it into auto stick mode.

My understanding is that when selecting raised shift points that the shift point is raised to 6400 for all upshifts (on the SRT8s). When you select raised shift points the rev limiter is also raised to 6550? Should be sufficient and I've never hit the rev limiter with only selecting raised shift points. When the pcm/tcm initiates a shift it takes the transmission some time to execute it. While the transmission is shifting the engine will continue to rev up. The engine is increasing revs faster during the 1-2 shift than the 2-3 shift etc. so there will be the greatest "overrun" during the 1-2 shift. 150 rpm should cover it but maybe it's close and every car is a little different. I think maybe the Jeeps rev faster in 1st than the LXs. If you're hitting the rev limiter with the shift point at 6400 and the limiter at 6550 then you should be JUST hitting it (even though the effect may be rather dramatic). Rasing the rev limiter above the point set by selecting raised shift points should cover it. Then when the transmission shifts, if you were bumping the rev limiter at 6550 before it may only go to 6600 before the transmission completes the shift. You should never see the 6700 limiter. As above, the danger is primarily with disabling automatic upshifts (Autostick Auto Upshift Disable) but I don't know if there are any other unusual situations where the engine might over rev. I do think you have a chance of floating a valve at 6700, but this is only from someone saying they did so and not from any personal knowledge, information or experience. Power drops off up there anyway so there is no reason to intentionally rev the engine that high.

The suggestion to log it is a good one to see what is actually happening. I'd first try to see if you are actually hitting the rev limiter. I use a different data logger so I'm not sure what pids are available on the Predator. Maybe something like the pedal position remaining on the floor and seeing the throttle blade close would be a good indication that you hit the rev limiter. I think the Predator only supports the standard pids so I'm not sure if DCx specific pids are available like current gear and target gear. The standard pids should be sufficient.

Hope that helps but it's just my personal, and relatively uninformed, 2 cents.

[Illss1]

I think you guys may be confusing some terms here. The rev limiter is a safety. I currently have mine at 6750, just cause I don't want it in the way with my shifts. Your car will only rev to the point of where you SHIFT at. So if you raise your shift points to say 6500, that's all the engine will see. You could have your rev limiter set to 12,000 and it wouldn't affect anything.

BTW, I ran 12.80's at the track last weekend with the raised shift points. No issues whatsoever.

Ur saying that what i'm thinking of is shift points rpms an not rev limiter ? Maybe, but i thought once u raise shift points an raise REV limiter in drive feature that whatever ur set at say (6800) that thats what ur limit is ? I guess i'm not understanding smt ......

I think Illss1 is saying that he set his rev limiter quite high because he doesn't ever plan on hitting it since the car will shift before it gets there. More than likely true in his case. Note that the predator will allow you to disable the automatic upshift feature in auto stick mode. If you disable the automatic upshift and put the car in auto stick mode it will hold the current gear until manually upshifted. In this configuration the car WILL rev until hitting the rev limiter. I do not have my automatic upshift disabled. First of all I'm just not good enough to beat the automatic upshift and second I do occassionally bump the shifter and inadvertently drop it into auto stick mode.

My understanding is that when selecting raised shift points that the shift point is raised to 6400 for all upshifts (on the SRT8s). When you select raised shift points the rev limiter is also raised to 6550? Should be sufficient and I've never hit the rev limiter with only selecting raised shift points. When the pcm/tcm initiates a shift it takes the transmission some time to execute it. While the transmission is shifting the engine will continue to rev up. The engine is increasing revs faster during the 1-2 shift than the 2-3 shift etc. so there will be the greatest "overrun" during the 1-2 shift. 150 rpm should cover it but maybe it's close and every car is a little different. I think maybe the Jeeps rev faster in 1st than the LXs. If you're hitting the rev limiter with the shift point at 6400 and the limiter at 6550 then you should be JUST hitting it (even though the effect may be rather dramatic). Rasing the rev limiter above the point set by selecting raised shift points should cover it. Then when the transmission shifts, if you were bumping the rev limiter at 6550 before it may only go to 6600 before the transmission completes the shift. You should never see the 6700 limiter. As above, the danger is primarily with disabling automatic upshifts (Autostick Auto Upshift Disable) but I don't know if there are any other unusual situations where the engine might over rev. I do think you have a chance of floating a valve at 6700, but this is only from someone saying they did so and not from any personal knowledge, information or experience. Power drops off up there anyway so there is no reason to intentionally rev the engine that high.

The suggestion to log it is a good one to see what is actually happening. I'd first try to see if you are actually hitting the rev limiter. I use a different data logger so I'm not sure what pids are available on the Predator. Maybe something like the pedal position remaining on the floor and seeing the throttle blade close would be a good indication that you hit the rev limiter. I think the Predator only supports the standard pids so I'm not sure if DCx specific pids are available like current gear and target gear. The standard pids should be sufficient.

Hope that helps but it's just my personal, and relatively uninformed, 2 cents.

Thanks for the responses guys ...... i can't stop it from bouncing off the limiter at wot .... would wheel spin have anything to do with this ?

[Mike_Levy]

If the wheels are spinning its going to hit the limiter every time. Theres absolutely no reason to be spinning all the way through a gear.

[Quick]

If the wheels are spinning its going to hit the limiter every time. Theres absolutely no reason to be spinning all the way through a gear.

That might not be true is it? Yes the engine will wind up faster when you spin the wheels but it won't necessarily hit the rev limiter before it shifts.

[Mike_Levy]

If they're spinning, really spinning, not just a short break in traction, 99% of the time you're gonna hit the limiter and put the car into limp mode.

[SRT8Tech]

I just went out and tested this whole thing. I have the raised shift points and put the limitter at +200. I put it in 1st autostick and just punched it to see what the rev limit was. I have the autostick disabled. I hit the limitter at 6500-6550. No limp mode but it just hit the limiter soft and then I shifted it. It wasnt a big bang then limp mode but actually a quite nice back off of the throttle when it hit the limitter. Pretty smooth. I dont se any problems with that on the stock valve train.

[Quick]

Did you log to check the rpm? The analog tach lags a good bit winding it up (and it's difficult to accurately read a peak on the EVIC tack with you foot on the floor. I'm surprised the throttle back off when hitting the rev limiter was described as "smooth". My experience was that hitting the rev limiter causes the throttle to be immediately cut to zero. It's like turning the ignition off and then you instantly go from acceleration g-force to engine brake g-force. Not exactly what I'd describe as "smooth".

[SRT8Tech]

Yep, it was a log I did. The max rpm was acutally 6538 so I believe the limiter was 6500. When I had the rev limitter above the +200 it did have the big bang then limp mode problem but so far it seems it wont do that at just the +200. It just kinda backed off the throttle % and no really harsh bang or limp mode. It didnt goto 0% throttle like it has done before. Also it was spinning bad but climbing in the RPM range slowly so it wasnt like just punch throttle and spin so bad it hits the limitter instantly. That might be why it wasnt as harsh as it normaly would be. I was at 25 MPH in 1st when I hit it. Not from a dead stop. It was hookin and spinning at the same time. If ya know what I mean. LOL

[Quick]

Ummm, traction control? Did you have the esp off? That sounds more like an ESP response.

You shouldn't have to punch it to find the rev limiter if you have disabled autostick upshift. You should be able to just creep up on it.