Cammed LS1 Auto/Stally too big?

[AlexH95]

At the risk of dragging up the dyno is only a tuning tool etc argument...250kw (335hp) for those mods and that cam seems a little on the low side. Imo you should be looking around 280-300kw.

This guy is closing in to 300kw, same cam on an ls1 (video loses audio during the pull unfortunately)

I have the following in my vx that I had tuned just before xmas at 267kw (358hp) on a stock cam.
1-7/8 4-1 Pacemaker headers
2.5" catback
100 cell cats
VCM OTR
3.9 truetrac diff gears.
Stock cam (as far as I know)

Dont know about your converter but maybe have another chat with your tuner !!

Yep, I know plenty of people with the exact same mods in a manual trans tho. sitting anywhere from 280-310rwkw. I mean I don’t understand how a highstall robs power?

 

[EYY]

My ls1 with a smaller cam around 232 234 on 112 centres with just over .600" lift was very strong in the top end and power curve flattened at about 6600rpm. If it feels lazy in the top end with that cam, there's probably something amiss.

 

[EYY]

Yep, I know plenty of people with the exact same mods in a manual trans tho. sitting anywhere from 280-310rwkw. I mean I don’t understand how a highstall robs power?

Histall is similar to slipping the clutch up to whatever the stall speed is and so plenty of energy doesn't make it to the output shaft below stall speed. They can reduce dyno figures significantly, but since they keep the engine in the powerband for much better drive-ability and performance. Histall won't impact high rpm performance negatively - quite the opposite.

My money would be on a tune issue providing the engine has been properly built.

 

[Chuckmeister]

Just throwing this out there as my tuner recommended this for a car of my age.
He suggested that if I didn't know when/if the fuel filter was changed then before the tune ...to replace it, which I did.
I'm wondering if maybe something simple like a blocked fuel filter might be leaning out your car and the tuner has tuned around it..

 

[Immortality]

I had the dyno sheet which I’ve unfortunately misplaced. I did notice the the torque curve shot up hard and quick but as the car revved out the torque curve was actually decreasing over the run. Could that be because of the stall converter maybe?

Torque is the ability to turn the wheels, HP is just a calculation of torque multiplied by RPM (and a constant). IT is normal for the torque curve to decline and still have the HP increasing with rpm.

If you check out this dyno sheet, you'll see the torque and HP lines intersect at about 5200rpm (this chart is in HP and Ft-lbs) and interestingly, to calculate hp from torque you use this formula, HP = Torque x RPM ÷ 5252

Metric dyno sheets (kw and Nm) look a bit different because the scaling differences.

Have you checked the trans fluid/levels? What fluid do you run?

 

[Heron SSV]

Why did you have it retuned? I assume you bought the car with the mods already done, was it an unfinished project? if it was tuned before, what were the figures then? It might be running out of fuel up top, or as mentioned before a blocked filter. Could also be the ingition system, might be the spark plugs or leads not firing properly or eficiently at high rpm. Definitely speak to the tuner you used, or speak to GM Motorsport as it looks like all the parts used was from them. Could also be the trans slipping at high rpm, are you running a trans cooler, or know whether it was actually built or someone just slapped a shift kit into it?

 

[AlexH95]

Why did you have it retuned? I assume you bought the car with the mods already done, was it an unfinished project? if it was tuned before, what were the figures then? It might be running out of fuel up top, or as mentioned before a blocked filter. Could also be the ingition system, might be the spark plugs or leads not firing properly or eficiently at high rpm. Definitely speak to the tuner you used, or speak to GM Motorsport as it looks like all the parts used was from them. Could also be the trans slipping at high rpm, are you running a trans cooler, or know whether it was actually built or someone just slapped a shift kit into it?

I had it retuned because the shifts points in the box were way out of whack for my liking. It was originally tuned back in 2017 so I thought it would be due for a fresh tune anyways. Which back then apparently made 250rwkw on another dyno. I then got it retuned which made the car a lot nicer to drive and it made an additional 26rwkw with a final figure of 250.5rwkw on a different dyno to the original one... the torque and power feels consistent so if it were the fuel would I be noticing any splattering or something? The tune and drivability of the car itself feels great and linear for the most part. I’d love to take it to GM or something and get it tuned but tbh it’d probably just end up with a higher dyno number and the same power anyways. I’m just here to see if it’s a proven fact that high stalls deprive top end power or something? Haha

 

[AlexH95]

Torque is the ability to turn the wheels, HP is just a calculation of torque multiplied by RPM (and a constant). IT is normal for the torque curve to decline and still have the HP increasing with rpm.

If you check out this dyno sheet, you'll see the torque and HP lines intersect at about 5200rpm (this chart is in HP and Ft-lbs) and interestingly, to calculate hp from torque you use this formula, HP = Torque x RPM ÷ 5252

Metric dyno sheets (kw and Nm) look a bit different because the scaling differences.

Have you checked the trans fluid/levels? What fluid do you run?

I haven’t checked levels or I’m unsure of what oils in it. It’s a 400rwkw rated stage 2 box as the car was originally going to be set up for a 150 shot at Calder but the previous owner had to sell due to certain circumstances. Although the box itself feels and shifts fine I believe. It does have a trans cooler attached to it too.

 

[Heron SSV]

I had it retuned because the shifts points in the box were way out of whack for my liking. It was originally tuned back in 2017 so I thought it would be due for a fresh tune anyways. Which back then apparently made 250rwkw on another dyno. I then got it retuned which made the car a lot nicer to drive and it made an additional 26rwkw with a final figure of 250.5rwkw on a different dyno to the original one... the torque and power feels consistent so if it were the fuel would I be noticing any splattering or something? The tune and drivability of the car itself feels great and linear for the most part. I’d love to take it to GM or something and get it tuned but tbh it’d probably just end up with a higher dyno number and the same power anyways. I’m just here to see if it’s a proven fact that high stalls deprive top end power or something? Haha

Dyno's are a tuning tool and figures can vary greatly, the only thing to look at really is the increase depending if any mods were done. I have a stock LS3 in a VK with a 3700 converter and TH400, it made 240rwkw, same combo (intake and full exhaust, but with a standard 6 speed box and converter) in a VF make around the 280-290rwkw, but again it depends on the dyno. High stall will change the way it makes power and how the curve looks on the dyno graph but at full throttle and high revs it shouldnt make a difference to the top end, those converters are designed to get the rpm's up to where torque is almost at it's peak as quick as possible, that makes it feel more responsive.

If it does have a fuel issue, it might not show all that noticeably, i.e. surging, fuel pressure could be dropping slightly and it isnt getting enough fuel. Thats a conversation for your tuner, they should have noticed during the tune whether it was getting enough fuel. When mine was tuned it was running out of fuel above 4krpm, I'm running a Walbro 460 so it has plenty of pump, turns out one of the lines in the tank had perished and was leaking a little bit.

 

[gtrboyy]

If it were manual + twin 3' exhaust probably be another 280-300rwkw car.

Yes you'll always have lower dyno figure having an auto then moreso with big stally,

Datalog to check everything behaves as it should....then go line your mate up at the track,yours should be fun as it's more suited for drags than roll ons.

I've had cars with 'low' dyno numbers that ripped hard with decent timeslips...also had high horsepower cars that felt average on street & crap timeslips so don't get too caught up with dyno numbers