How much MPG did you lose modding?
10-20-2018, 02:11 AM
#1
TECH Apprentice
Thread Starter
How much MPG did you lose modding? My car used to get about 23 mostly hw driving before the mods in my sig, I was expecting it to lose some but on the same trip where I used to get 23 I got 16 now? Now it doesn't really matter since it's hardly driven but does this seem right with my mods?
10-20-2018, 07:18 AM
#5
I can see poor mileage if you don't have a lock up converter. The key is getting an auto locked quickly for the gear your in as soon as your off the gas depending on your driving style. My Vette 6speed auto sees 30 mpg /18.5 city often, having a really good exhaust system. It runs leaner and with higher timing and improved shift pressures and quicker lockups giving the benefit of way better track times(11.8's) and less fuel consumption than stock while cruising. Big heads (ported) would be an improvement as well with good gains but its all down hill when getting into big cams and lower gears/no lock ups or no over drive. My T/a is a good offset running in the 6's. It has a moderately big cam and 4.10's with an a4 so it works good for dual purpose even gas mileage wise, if you don't step on it and go the speed limit.
Last edited by handyandy496; 10-20-2018 at 07:38 AM.
10-20-2018, 08:08 AM
#6
12 Second Club
When my car was stock, I averaged about 20mpg with a combo of highway and city driving. Now, I average about 16-17mpg with heads/cam/bolt-ons. I haven't driven it long distances since the heads/cam swap. After the bolts-on, I lost about 2mpg on the highway. I figure the heads/cam lost me another 2 mpg on the highway. I think I was getting about 24-25mpg on the highway when it was stock.
My car came with a 4L60e and a .323 rear end. Now, I have a 4L80e and the same rear end.
My car came with a 4L60e and a .323 rear end. Now, I have a 4L80e and the same rear end.
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10-20-2018, 09:38 AM
#8
TECH Apprentice
Thread Starter
Oops, forgot to mention that the converter was in the car before the rest of the mods, so with the converter before the mods I was getting 23. Just the heads/cam/intake/headers cost me 7 mpg. Seems some people lost mileage and some didn't.....could it be in the tune? I'm thinking of some high hp newer cars that have a street vs track setting that can be changed on the dash, is this 2 separate tunes maybe?
10-20-2018, 10:15 AM
#9
Dano, if the transmission is fresh and in good shape I'd have someone look at the tune. Several members are very good with tuning, I suggest asking a few of them to look at the tune fike.
OCD mode, sorry for long post, but here are some details for compare. I religiously check mpg, GPS miles, verified mpg. I also get a kick out proving the mpg claimed by road tripping with them in car and proving it.
My impression is a lot of tuners are horrible with drive ability tuning. They focus and spend time only on the power tuning. They think performance car so MPG doesn't matter. So according they put little effort into tuning the drive ability which includes MPG in my book.
MTI (original company) had a great reputation for good mail order tuning. Jason had worked out the details and did very good LS1 Edit mail order tunes. My car could do 27 mpg highway with 4.10's. A friend had the same heads & cam with 3.90's and got 18 mpg highway. He had a good power tune and a lousy drive ability tune. This was back in 2002.
Mike Norris at Norris Motorsports does very good drive ability tuning. He did my RS with 383 LS1 and I'm very happy.
He also did a very good tune for the 99 TA's 416. I already knew I'd screwed up the gas mileage with the T56 Magnum's .62 over drive 6th gear before the 416 went in the car.
02 Z28 - stock LS1, A4, 2.73's, weekly driving 19-20 mpg, highway 27.0 -27.5 mpg
91 RS - stock, 305 TBI, 700R4, 2.73's - weekly driving 24.5 to 25 mpg, highway way 32-34 mpg
91 RS - resto-mod, 383 LS1, T56, 4.10's, 8.8 rear- weekly driving 18 mpg, highway 25-25.5 mpg.
72 Vette - 350, 9 to 1 compression,headers, Isky 270 cam (222/222), TH400, 3.08 - weekly 14-5 mpg, highway 17 mpg
72 Vette -383, 10 to 1 compression, 240/250 cam, headers, TH400, 3.08 - weekly 13-14.5 mpg, highway 16 mpg
72 Vette - Dart 400, 10.85 to 1 compression, 230/236 cam, ported intake & heads, headers, TH400, 3.08 - weekly 14-16 mpg, highway 17 -19 mpg
Gains from compression, better tune, porting, rebuild of TH400 and weight loss of ~200+ pounds
99 TA - stock & bolt on, LS1, T56, 3.42's - weekly 23-23.5 mpg, highway 32.5-32.8 mpg
99 TA - TEA heads & 224 XER cam, LS6 intake, LT, 4.10's, MTI mail order tune, weekly 20-21 mpg, highway 26-27.5 mpg
99 TA -TEA heads & 224 XER cam T56 Magnum
62 OD, 4'10's 8.8 rear, dyno tuned, weekly 18-19 mpg, highway 21-23 mpg
99 TA - LS 416, 237/245 cam, T56 Magnum .62 OD, 4'10's 8.8 rear, dyno tuned, weekly 15-16 mpg, highway 19-20 mpg
The T56 Magnum w/ .62 OD killed the TA's otherwise good gas mileage.
OCD mode, sorry for long post, but here are some details for compare. I religiously check mpg, GPS miles, verified mpg. I also get a kick out proving the mpg claimed by road tripping with them in car and proving it.
My impression is a lot of tuners are horrible with drive ability tuning. They focus and spend time only on the power tuning. They think performance car so MPG doesn't matter. So according they put little effort into tuning the drive ability which includes MPG in my book.
MTI (original company) had a great reputation for good mail order tuning. Jason had worked out the details and did very good LS1 Edit mail order tunes. My car could do 27 mpg highway with 4.10's. A friend had the same heads & cam with 3.90's and got 18 mpg highway. He had a good power tune and a lousy drive ability tune. This was back in 2002.
Mike Norris at Norris Motorsports does very good drive ability tuning. He did my RS with 383 LS1 and I'm very happy.
He also did a very good tune for the 99 TA's 416. I already knew I'd screwed up the gas mileage with the T56 Magnum's .62 over drive 6th gear before the 416 went in the car.
02 Z28 - stock LS1, A4, 2.73's, weekly driving 19-20 mpg, highway 27.0 -27.5 mpg
91 RS - stock, 305 TBI, 700R4, 2.73's - weekly driving 24.5 to 25 mpg, highway way 32-34 mpg
91 RS - resto-mod, 383 LS1, T56, 4.10's, 8.8 rear- weekly driving 18 mpg, highway 25-25.5 mpg.
72 Vette - 350, 9 to 1 compression,headers, Isky 270 cam (222/222), TH400, 3.08 - weekly 14-5 mpg, highway 17 mpg
72 Vette -383, 10 to 1 compression, 240/250 cam, headers, TH400, 3.08 - weekly 13-14.5 mpg, highway 16 mpg
72 Vette - Dart 400, 10.85 to 1 compression, 230/236 cam, ported intake & heads, headers, TH400, 3.08 - weekly 14-16 mpg, highway 17 -19 mpg
Gains from compression, better tune, porting, rebuild of TH400 and weight loss of ~200+ pounds
99 TA - stock & bolt on, LS1, T56, 3.42's - weekly 23-23.5 mpg, highway 32.5-32.8 mpg
99 TA - TEA heads & 224 XER cam, LS6 intake, LT, 4.10's, MTI mail order tune, weekly 20-21 mpg, highway 26-27.5 mpg
99 TA -TEA heads & 224 XER cam T56 Magnum
62 OD, 4'10's 8.8 rear, dyno tuned, weekly 18-19 mpg, highway 21-23 mpg
99 TA - LS 416, 237/245 cam, T56 Magnum .62 OD, 4'10's 8.8 rear, dyno tuned, weekly 15-16 mpg, highway 19-20 mpg
The T56 Magnum w/ .62 OD killed the TA's otherwise good gas mileage.
Last edited by 99 Black Bird T/A; 10-20-2018 at 10:33 AM.
10-20-2018, 10:38 AM
#11
ModSquad
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When I drove the Chevelle home from Birmingham the day I bought it, with the 350 in it, it prolly got like 17-20ish.
The 6 liter I built got 22. My new 434, I haven’t checked yet, but I’d venture to say a legit 7-10. It might do better on the interstate. Doubt it. I can pass anything on the street, except a gas station.
The 6 liter I built got 22. My new 434, I haven’t checked yet, but I’d venture to say a legit 7-10. It might do better on the interstate. Doubt it. I can pass anything on the street, except a gas station.
10-20-2018, 02:29 PM
#14
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Originally Posted by 98CayenneT/A
A lot
When my 346 was maxed out I was getting 18 mixed and 23 highway. On the 428, it is 12-13 around town and no full tanks of highway driving to know what it is on the highway.
I find the cam is about the biggest influence on mileage. Up to a point, no big deal. After a certain point, mileage falls fast with duration. Displacement also. After that, gear. But again, 3.73 I dont think made a big difference. 4.30, YUGE difference. But the 18/23 on the 346 was also on 4.30.
10-20-2018, 05:37 PM
#15
TECH Apprentice
Thread Starter
I guess it just depends on the build then. it's no biggie since I hardly drive the car, just something I noticed after taking it out of state for a couple days. Years ago, I had a 1970 Chevelle with a built 427 and it was slightly bad also.
10-20-2018, 06:07 PM
#16
TECH Senior Member
Slightly bad, as in when filling the tank you had to shut it off to keep it from catching up to the pump? lol
10-20-2018, 07:17 PM
#18
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10-20-2018, 08:52 PM
#20
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Originally Posted by LLLosingit
My S10 with stock 4.3/4l60 got 16-17mpg and made about 170hp, Dropped in an LSA supercharged LY6 and TR6060 and now I get about 20-25mpg on e-85 and makes 550+hp. It will cruise at 70mph at 1,400 rpms.