Srv rpm

[Josh19881]

Got my tune pretty good on my 13 ram 5.7. Did the 392 cam swap a while ago. Recently built a forged 5.7 and thw same cam but new. 6.4 truck intake at the same time.

My question is srv low rpm enable, hi rpm enable, and med rpm disable.. I see alot of other tunes for 6.4's use lol rpm enable around 4400 - 4800 rpm and hi rpm enable and med rpm Disable at 8160. Mine is lo enable at 1800 and disable at 3450.
Could someone maybe explain how the tables work? I feel like I can make this part of it a bit better.

Thank you.

[LilSick]

3 adjustments and but 1 matters - thx dodge - thx hpt

the 'low enable' is the rpm that the runners shorten up at

4700 is stock setting and a lil too low - it causes a dip in the torque curve

raising it to 4800-4900 will take the dip out and looks real purdy on a dyno

i dont race on a dyno tho, i run my car at the track

finding the correct setting for the srv has to do with shift points, roll out, and what ratio diff is in your car - but i promise 1800 rpm is not what it wants

[Josh19881]

I didn't think it wants 1800 on lol
I believe it's something with the 5.7 trucks, I have a couple stock 5.7 ram tunes and they both are 1800 lo enable and 3450 disable. Really odd.
So I'll set lo to 4800 and max the others and go up and down from there to see what it likes.

Thank you so much for your help!

[LilSick]

makes me wonder if those tables are accurately labelled ?

yer welcome

[PurpleRam]

1st I have to ask, 6.4 Manual cam or the MDS cam ?
If your 13 is one of the Many QC 4x4 that seam to be everywhere, run that SRV Long runner till 5k RPMs,
The 392 cam in a 392 makes peak Tq around 4200ish, in the 5.7 it makes at around 4400-4700 depending on Altitude and Tq curve. the idea is to have the valve change over @ 400 RPMS above Peak Tq ,
Every tune is different ,
What I do is, set the Lo to 8160, make a log, record Calculated Load and Tq Request , Run it up in 1st gear till I feel the truck stop pulling, note the RPM you felt momentum lessen, add 400 RPMs , then go make a few spirited pulls thru the gear, doesn't have to be WOT , look at the logs, see where it's peaking at, add 400 RPMs , compare the results , and adjust from there.


Customer's 2013 RC4x2's with the 6speed and 4.88's we have the SRV come in at 4200, that's where that truck runs the best (12.10@112) my shop errand boy's 14 QC4x2 , the LO SRV is set to 8160 , it's in short mod all the time.

If you go down the N.O.S rabbit hole, the SRV comes in handy if you time it around the N.O.S shot.

[LilSick]

i never did it so have no experience but it sounds backwards? the same cam in two motors comes on earlier in the one with larger ports and valves? seems like it would be the opposite? i have always been a fan of displacement and compression, must be whats happening here?

you meant if the low is 8100 the manifold will stay long yeah?

[LilSick]

you probably don't want your shift recovery point to be just below the changeover point.

right, thats why gear roll out which trans and shift rpm all play into it and it doesnt really matter what the dyno says

[Josh19881]

1st I have to ask, 6.4 Manual cam or the MDS cam ?
If your 13 is one of the Many QC 4x4 that seam to be everywhere, run that SRV Long runner till 5k RPMs,
The 392 cam in a 392 makes peak Tq around 4200ish, in the 5.7 it makes at around 4400-4700 depending on Altitude and Tq curve. the idea is to have the valve change over @ 400 RPMS above Peak Tq ,
Every tune is different ,
What I do is, set the Lo to 8160, make a log, record Calculated Load and Tq Request , Run it up in 1st gear till I feel the truck stop pulling, note the RPM you felt momentum lessen, add 400 RPMs , then go make a few spirited pulls thru the gear, doesn't have to be WOT , look at the logs, see where it's peaking at, add 400 RPMs , compare the results , and adjust from there.


Customer's 2013 RC4x2's with the 6speed and 4.88's we have the SRV come in at 4200, that's where that truck runs the best (12.10@112) my shop errand boy's 14 QC4x2 , the LO SRV is set to 8160 , it's in short mod all the time.

If you go down the N.O.S rabbit hole, the SRV comes in handy if you time it around the N.O.S shot.

It's the manual cam of course. I did set it to 4800 the other day and it really does wake up the lower rpm range. Stock settings it felt like it would fall over until around 3500 or so.
I actually had to get hp tuners to add it to the beta editor for me since it wasn't normally in there. I'll play around with lowering it and see if it picks up any.

Nitrous will be a while lol. That was the reason for doing forged.

Also it's a 13 4x4 3.55, it's a 4 full door I get them mixed crew or quad cab. The bigger one lol.

Thanks again everyone!

[PurpleRam]

With that size truck, I think 5200 is where it’ll feel best,. do few 3/4 pedal (@your 4800 setting), try and keep it from going into WOT/PE tables add 200 rpm’s , repeat, add 200 more , you will feel where it wants to be,
stock size tires?

[Josh19881]

Stock 275 60 20s.
The truck is heavy so it's definitely not a racecar.

If I'm monitoring actual and desired torque would that be an indicator of gain or is it just for torque management?

[LilSick]

yeah ya cant go by that

can look at aircharge and the like but the track is how ya know

or like he saiid, 3/4 throttle seat of pants

[Josh19881]

I'll just do seat of the pants feel lol. May not be the best or perfect but it's a daily driver and some towing. Probably won't ever get to a dyno or track with this.

[PurpleRam]

Stock 275 60 20s.
The truck is heavy so it's definitely not a racecar.

If I'm monitoring actual and desired torque would that be an indicator of gain or is it just for torque management?

Monitor actual torque, what you are looking for is not so much an increase in Tq as much as where the peak is happening, the more you tow the higher you want the changeover.

That's the advantage of the SRV, we can use it to move the Peak Tq, Not a lot but enough to make a difference especially with the RFE65 . the SRV ......it's both a dual plane and a single plane intake.


even though the difference between the 392(49ci) and 5.7/345(43ci) is roughly 6 CI per cylinder, the 5.7s pitiful 1.57 Exhaust valve makes it act like it's a 39Ci per cylinder engine.

392ci with 215/[email protected] has a Tq operating range is 1000-5000 rpm, while the 5.7 with the same @.05 specs is 1200-5200, when the Eagle heads were being designed the idea of a 1.60 exhaust valve was thrown around , but the 1.57 valve kept the Tq curve flat

late 05 one of the projects that dropped in my lap was" test 5.7 with 6.1 top end(heads/intake/cam)" early on in those sessions I kept running out of Intake manifold,took a R5/P7 Intake welded up some adaptors, ran the mule with that intake and BOOM, the thing made power all the way up 7100.

One other test I did afew years back was a SRT392 manual cam engine but with the LS firing order, 1-8-7-2-6-5-4-3, instead of 1-8-4-3-6-5-7-2..... picked up 30HP , 505hp@5900, vs stock 485(ish)@6100 and 25Ftlbs , 500@ 4000 vs 475 @ 4100(ish).....and No "dyno hump."


EDIT: I think the Aftermarket cam guys are missing out, by not grinding some cams to utilize the VVT function, I did a custom grind cam test back in September with a 2016 ram, , 220/[email protected], lift 545/560, 115lsa 128* swing like the stock 5.7 cam, 385rwhp@6000 and 383 Ft @4800 , with the stock truck intake Iron manifolds. and a cat back exhaust., did have a vararam CAI. stock Valve springs.

[Josh19881]

Monitor actual torque, what you are looking for is not so much an increase in Tq as much as where the peak is happening, the more you tow the higher you want the changeover.

That's the advantage of the SRV, we can use it to move the Peak Tq, Not a lot but enough to make a difference especially with the RFE65 . the SRV ......it's both a dual plane and a single plane intake.


even though the difference between the 392(49ci) and 5.7/345(43ci) is roughly 6 CI per cylinder, the 5.7s pitiful 1.57 Exhaust valve makes it act like it's a 39Ci per cylinder engine.

392ci with 215/[email protected] has a Tq operating range is 1000-5000 rpm, while the 5.7 with the same @.05 specs is 1200-5200, when the Eagle heads were being designed the idea of a 1.60 exhaust valve was thrown around , but the 1.57 valve kept the Tq curve flat

late 05 one of the projects that dropped in my lap was" test 5.7 with 6.1 top end(heads/intake/cam)" early on in those sessions I kept running out of Intake manifold,took a R5/P7 Intake welded up some adaptors, ran the mule with that intake and BOOM, the thing made power all the way up 7100.

One other test I did afew years back was a SRT392 manual cam engine but with the LS firing order, 1-8-7-2-6-5-4-3, instead of 1-8-4-3-6-5-7-2..... picked up 30HP , 505hp@5900, vs stock 485(ish)@6100 and 25Ftlbs , 500@ 4000 vs 475 @ 4100(ish).....and No "dyno hump."


EDIT: I think the Aftermarket cam guys are missing out, by not grinding some cams to utilize the VVT function, I did a custom grind cam test back in September with a 2016 ram, , 220/[email protected], lift 545/560, 115lsa 128* swing like the stock 5.7 cam, 385rwhp@6000 and 383 Ft @4800 , with the stock truck intake Iron manifolds. and a cat back exhaust., did have a vararam CAI. stock Valve springs.

Tons of useful information! I really appreciate that!

For me it feels about the same setting the srv at 4800-5200. Definitely smoother pulling than the factory set point. I feel like I'm missing a bit of power because around 4000rpm or so I had to drop timing quite a bit to keep knock retard down 1.5 and below. I have timing 11-14.5 in that area. I was thinking it was due to the forged pistons but it did it with the original engine as well..

Overall it's alot better than it was and pretty happy with it!

[LilSick]

5.27.png

that ^^^ is where dodge sets it for 3/4 ton truck

if that were my truck i would put it at 8100 and never let it shorten up

motor would hardly ever see 4500 either tho - so there is that

[Josh19881]

5.27.png

that ^^^ is where dodge sets it for 3/4 ton truck

if that were my truck i would put it at 8100 and never let it shorten up

motor would hardly ever see 4500 either tho - so there is that

I saw that on the 2500 6.4 tune I have and that's what prompted my initial post. I have a couple ram 1500 5.7 tunes along with mine and they were set to enable at 1800 and disable at 3400. It was obviously losing a noticeable amount of low end power.

I do run it kinda hard now and then but your right, hardly sees 4500+. It does seem to like it at 5000 where it currently is. I've changed it a few times up and down.

[LilSick]

the 1500 srv tune makes about as much sense as the stoich being different for ea pump gas motor dodge builds

[rays04gtx]

the 1500 srv tune makes about as much sense as the stoich being different for ea pump gas motor dodge builds

EA? or NA ?

Keep in mind the 5.7 Truck Manifold runner cross-section is smaller than the 6.4 truck, and length is about 3 inches longer over all, also 5.7 truck cam Vs 6.4 Truck cam,

also Mass to be delivered is different for the 6.4 Truck intake vs the 5.7 Truck and the 6.4 SRT.

[LilSick]

the mass should be different... the manifolds, valve size, compression ratio and displacement are different

but if they all are burning the same fuel why should the stoich be different?

[rays04gtx]

the mass should be different... the manifolds, valve size, compression ratio and displacement are different

but if they all are burning the same fuel why should the stoich be different?

because of the cooling factor of the AFR , the Idea is a 6.4 truck engine is going to carry a heavier load on the engine, same with the Hellcats, set Stoich to run fat, and piston/Exhaust valve Temps stay 15% cooler.

most of the 2000's stuff ran .0694(5) 14.4 Target AFR , Eagle 5.7s .0688(14.53) while the 6.4 Truck runs .0720(13.88) HellCats are .0722.


when I do a tune for a Eagle headed QC 4x4 truck I set stoich @ .0714(14.0AFR) if it's got stock pistons,.0700 if it's forged .