Car is ZZ4TPI 3:23 auto, edelbrock intake, slp runners, cold air intake.
This tank was 18.7mpg and mostly semi-highway driving, 45mph to 65mph with some city mixed in and some start and stop.
Does this sound about right for the ZZ4TPI?

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Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

That sounds about right for a lot of in town driving with an occasional 1/4 mile blast. LOL

I get close to 30 MPH on the highway because I have highway mode fuel and spark enabled in the ECM.

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1992 Z28 5.7 TPI

ZZ4 longblock
Harland Sharp roller rockers
Accel base and SLP siamesed runners,
52MM SLP Throttle Body
Hooker Headers & Flowmaster catback
MSD6A ignition
aluminum driveshaft
World Class 5-speed

 

Hey guys,

I don't even think of that much on mine. Sometimes it seems I'm getting barely 13mpg.

-- Joe

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/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
1989 Formula 350 4-bolt mains, Forged .030 TRW pistons, SLP 51010 Roller Cam, Comp-cams roller lifters,
Summit 1.5 roller rockers, World Products Sportsman II 2.02/1.60 heads, Edelbrock TPI Intake,
Cloyes Double Roller, timing chain, Mellings oil pump: 13.5 @ 100.23 MPH

Since close of track : Ported SLP runners, Ported Plenum, AFPR, Autometer 100lbs gauge, A/F ratio gauge.

http://www.joesperformance.com

 

What exacly does highway mode change. I know that you change it when you program the prom but does it have variables or just on and off. If it does what are the variables.

 

Unless you have the EGR piped over to the exhaust manifold, this sounds about right. The ZZ4 engine doesn't have the EGR passages in the heads, so you have to run an external tupe over to #8 cylinder...

 

This sounds like a OXYMORON to me:
High Performance Engine that cost big bucks
and now worrying about his GAS Mileage.

 

This sounds like a OXYMORON to me:
High Performance Engine that cost big bucks
and now worrying about his GAS Mileage.

Actually, I'm not worried about gas mileage. I use it as a gauge to see how the car is running. Scanners are nice but I've seen cars that look good on scanners and suck gas when they should not. I'm not rich by any means and don't have money to pissaway on a car getting crappy MPG when it should be getting better mileage. And I didn't consider the ZZ4 a "big buck" engine.
But hey, thanks for that constructive input!
I'm sure it's made everyone on this board smarter!



------------------
Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Hey, I used to get 19 city on mine (never really measured the highway mileage), ZZ4 motor, T5, 3.23 rear, E4ME Quadrajet. If you're getting almost that with an automatic in mixed driving, that sounds pretty decent to me.

I didn't take it easy on my car either, and never got worse than 17mpg.

 

Thanks 99Hawk. Just making sure I'm in the ballpark!

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Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

wait did u put tpi on a crate motor? if u did can u give me some tips and how u did it thanks

 

I had already converted my 89 RS convt to TPI from TBI. So the hard work was done. The fuel pump in the gas tank, wiring harness etc. The only problem I ran into with the ZZ4 was my engine oil cooler would not fit with the big harmonic balancer, the passenger side head was missing one mounting hole for the serpentine set up, I had to reuse my stock L98 valve cover so the gromets would be correct. I also had a stock 92 intake at the time that Ihad to ahve machined so the center mounting holes would work. I've since replaced that with an aftermarket intake that is machined for new and old style heads.

------------------
Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Rob P and or crucial what kind of 1/4 times are you running?

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1991 Z28 ZZ4 with LPE superram base, SLP runners, LPE 58mm T-body,Random Technology ramair,TES headers,24#svo injectors,ZEX nitrous,Walbro 255lph f-pump,Accel AFPR,Random Technology catback,!cats,and mutch more.

 

Sorry, no track times yet. Ran 13.81 with a L98 in the same car so I'd guess low 13's with my stock tranny.

 

I averaged about 19 MPG and got as good as 25 mpg highway with my TPI ZZ4. Now I average 17 MPG and get 22-23 MPG with the bigger cam and highway mode turned on. It was under 20 without it...

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH (2.10 60')
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

Thanks Kevin, I really gotta get some chip burning stuff one day. I too have LT4 hotcam waiting to go in and an LT1 intake waiting to be modified.

------------------
Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!