Is the TU5JP4-S more economical than TU5J4?
 

Is the C2 vts engine more economical than the saxo vts one?. According to manufacturers figures it's 8 mpg more combined. That's in a c2 to, so certainly would be even better in Saxo with less weight. thanks

Im running a JP4 with J4 cams and valve springs. its noticeably better on fuel and a miles more driveable engine. 125 miles to £20 driving to work which is 75% town driving and being sat in traffic.

my jp4 in my track car... which is a 110bhp spec ... not fitted j4 cams yet seams very good on fuel :)

My JP4S engine used to struggle getting 60 miles to 10 litre's.

Found it had a leaky injector lol. Since fixing that, I got 78 miles from 10 litres with 2 spirited drive's.

Which is alot better, i'll take it easy on the next 10 litre's.. see what it get's.

how do you drive?

with my xsi i am getting roughly 120 miles to £20, driving to work, although there are a few places that i do give it a boot full. lol

120 miles to £20 (15 litres) in the J4 I have :)

main difference in fuel economy between the engines is the management system and the emission specs the ecu is set too + fly by wire throttle .
even the latest j4 engined saxo,s ran quite a bit richer than any tu5jp4 .
tu5jp4 runs lambda 1 up to 100%throttle angle up to 5000rpm ,then open loop omly above 90%throttle up to rev limter+ never any acceleration fuelling to the extent of the j4
j4 only ran lambda1 up to 4k and 70% throttle angle at any rpm and open loop above 4k+70%throttle
jp4 very slightly higher comp as well

Pretty much all jp4's in saxos are running on J4 management though, so i imagine they won't be as good on MPG as the C2 with the proper ECU.