MPG at different levels of NA tuning/Advice on JP4 Crank

11th July 2009, 23:59

Just wondering what kind of MPG is achieved depending on how far you go on an NA setup. Say in these stages;

- Mild cams and breathing mods (PH3s, 708s etc). Standalone
- Mild cams and TBs. Standalone
- More lairy cams, high comp forgies, TBs, Standalone

Also whats the day to day drive ability of the third option? I understand that the first option often brings better MPG than std due to the remapping.

Cheers

12th July 2009, 00:05

I averaged 34mpg in the "198bhp" saxo, averaged 40 in my one on 708s with wideband, averaged slightly less with standard(with and without breathing mods) vts.
Out on track or when thrashing it, it almost all depends on how much power you're making, providing it's running efficiently. Can thrash standard all day long and get 25-30mpg, down to about 20 on track. With 708s it was a few mpg worse, with bodies etc it was pretty damn awful on track lol

If you intend to use the car daily i'd stick with the std ecu or a pred, something that uses the original inlet and idle control valve.

12th July 2009, 09:02

i found vts on ph4 cams with jenvy boddies headwork breathing mods etc on track i was getting 12-18mpg

12th July 2009, 14:09

Cheers lads.

What kinda of low down driveability did you have with your setups? Eg is it likely to stall at junctions, chugg when pulling out etc?

Also a slightly off topic question, are the JP4 cranks good for high level NA tuning? At the moment my engines in bits after the valves bounced, Im trying to work out what route to take now to save time and hassle. Options are;

- Buy all the parts to get my current lump running again, HG kit, Cambelt Kit, auxiliary belt, head bolts, valves. Roughly £280 in parts

- Buy a second hand JP4 lump, use the valves out of that, buy the rest of the parts such as HG kit, sell off the cam and coilpack covers to make a bit of money back, keep the bottom end and head and slowly build this engine up over time with high comps, TBs and lairy cams etc (hence why I need to know if the J4 crank is better as Ill have to source a J4 bottom end), cost around £350 but works out cheaper long term

I want the best I can get out of the lump NA wise, whilst retaining realistic MPG and driveability as its my day to day car for the next 3 years at least whilst Im at Uni. If a really highstrung well sorted engine wont bring that Ill spend money getting the pistons out and properly machined rather than emeryclothing them down, and just go for the PH3/708 setup. Although I very much doubt Id be happy leaving it there so Im hoping you can give me good news about the JP4 crank lol

12th July 2009, 20:16

Bumpage

13th July 2009, 00:24

i get around 30mpg on a cammed vts with dta management and innovate lc-1 wideband.

14th July 2009, 02:10

Thats pretty good too, could live with that