£gettign more power from 3.5/3.9

[Ralphh85]

ok soon will have car running with an only 3.5 efi range rover engine in it.

the RR engine isnt ideal as it has alot of torque but not much power and being in a light car i could do with power ore than torque.

my main aim being power i have been told that i should go with a 3.9 as the bigger ones are only good if you trying to get torque, is this true?

keeping torque to moderate levels is an advantage as it will be less likely to blow things up, tho i dont see that being an issue.

my main thoughts where a better cam, hopefully to maybe 6krpm limit, probly after market ecu, and maybe ported heads. and anything else which was required to do that, (std pistons/rods ok?).

what kinda power output would i be looking at and any idea on what cost it would be? cost isnt n issue but the more it is the longer it will have to wait and also will buy parts bit by bit as unfortunately im not loaded!

Ralph

[kiwicar]

decent tubular exhaust manifolds matched to ports , stage 1 heads (with SD1 valves) matched inlet (but not matched to the gasket, matched to the inlet ports) uprated cam (225 deg at .05 ish) fuel mapped and a carefully assembled bottom end with about 10:1 cr should get you 210 to 215 real BHP and a red line of 6k or just shy (the tappets will limit you). This won't cost the earth just time and care.
Lighten the lot raise CR to 10.5 to1 spend £600 on head porting put in fancy tappets and a more radical cam and rocker set up you may get 230 bhp and 6300 revs on a good day. Will cost alot.
Mike

[Ralphh85]

when you say fuel mapped, can you map the original ecu or would it be an after market job?

also is that based around a 3.5 or 3.9 and which would you recomend for what im doing?


to be fare i should be very happy with 215bhp!! any idea on torque output? 230ish?


Ralph

[Teesdale_landrover]

ralph since your putting it in a metro i think you could go a bit wilder on the camshaft perhaps.

one things for sure if you take it apart it will need new cam/lifters/timing chain certainly

you cant chip the 3.5 ecu but you can get an aftermarket one, but i would change to the 3.9 hotwire system and get a chip for that (iro 350)
there are a few mods you can do to the 3.5 with some jaguar parts to better the injection system.

another thing sometimes overlooked is the injectors tend to deteriorate might consider getting them reconditioned to replace lost bhp

the crank on the 3.5 is not cross bolted into the block just has big bearing caps, you can get arp studs for these which are recommended

[Ralphh85]

i agree on the wild cam bit, kiwicar mentioned "225 deg at .05 ish" where would be the best place to get cams from? piper or kent or from a retailer like V8D?

im not going to use my 3.5 engine as its a flapper for a start and i want to drive the car with it in get another engine and do that engine up in my own time/as money permits.

is the chip for the 3.9 hotwire a piggy back thing? does it do just fuel or ignition as well? presuming its only fuel how do i change the ignition?


Ralph

[Ian Anderson]

Build it and drive it first

After you have it on the road you may find you do not need so much extra.

Remember the torque will accelerate the car but a big HP figure gives bragging rights in the pub!

I remember when I raced International Karts I was after more power and an "old hand" said no get the handling sorted. So I dod a load of work on the handling / stering geometry etc and knocked 1.5 scs of my lap time with the same engine! Only then was it worthwhile hotting the motor! I did the motor and it lasted 28 laps! (A fun 28 laps but really expensive)

Ian

[Ralphh85]

Build it and drive it first

Remember the torque will accelerate the car but a big HP figure gives bragging rights in the pub!

correct to a point, when im racing its gonna be using the most power the car has, you wouldnt race up a drag strip using the RPM band near peak torque?

obviously having a higher torque value will up speed a bit as when you change down a gear you will be putting more torque to the wheels.

i will defiantly get the car driving ont his engine as i intend to MOT it and use it as i only have use of this car ('99 punto 60!!!) for a few months. and i want my car running again

car handled well and should be ever better as will now have coilovers and double wish bone suspension all round, same with vented disks.

experience tells me i will always want more power!


Ralph

[kiwicar]

For cam I wouldn't go to far too soon, if this is a mid engined metro with an LSD then I think you want to get the transition onto throttle as smoothe as possable rather than outright power and torque hence the fairley conservative cam surgestion (for the same reason I would go aftermarket ECU.
Try looking at http://www.compcams.com/technical/Catal ... 26-227.pdf it is for the GM patterns, you can choose a profile and get it ground onto a Buick 215 blank as a custom, I would contact them by Email as they don't understand an english accent but it is quite a simple process to order one (alot of the cams sold as rover are infacte Comp Buick profiles).
Mike

[Ralphh85]

where would you go for the ecu? and also the stage 1 heads then?

you may well be right there, the main reason for wanting as close to 6k as i can get is mainly as its moderately low geared. tho i have the highest gearing possible with my gearbox

26mph per 1000rpm in top, so it would be nice if it was free revving quite far up the scale.

cheers for the advice!


Ralph


edit, i cant find that cam you mean on that site? presume its not similar to any of the uk produced ones?

[Ian Anderson]

Ralph

At 6k you'll be doing about 155 mph In reality I don't think a Metro was ever designed aerodynamically to do that sort of speed.

I'd expect with the light weight of the Metro body and that gearing you'd see about 130 on a fairly standard motor

By the way the gearing is about the same on my GT40 - expect about 160 top end out of my balanced, well breathing, hot cam engine and the acceleration is great but above 120 mph she gets light on the frint and I chicken out first!

Ian

[kiwicar]

Hi Ralph
For choice of 3.9 or 3.5, you probably would see only 10 or so extra bhp on the 3.9 if that and probably 300 revs lower, the heads limit the rover, you would see 30 to 35 extra lbft of torque again probably 500 revs lower and the power will drop off far quicker on the 3.9 it may come on the power 200 to 300 revs sooner but I would think it will make the engine more all or nothing to drive, again not so good with your car . if you have a 3.5 go with that if you have a 3.9 then look for a cam with 218 or so of inlet timing and 230 of exhaust and a lobe seperation of 112 to 114 degrees it would "soften" the throttle and allow the engine to over rev ( though it may drop 5 or so bhp over a straight 222/228 112 pattern 108 LSA cam).
As far as mapable ECU for the rover I would go for the VEMS or megasquirt units as the prices are the best, first choice would be a vems as there is now such good support for it on this forum and the VEMS unit is easier to get running with wide band lambdas. the MS is still a good choice and may still be a £50 quid cheeper to get going with but with VEMS you will find someone here will have a map that is 95% there from the start.
EDIT
For the head work, do it yourself, buy the SD1 valves and guides off one of the forum sponsore or Ebay, same for a set of uprated high lift springs and find one of the many books that tell you what to do (I've posted a couple of titles on here already but I'l go look them up again if you can't find them) or again get one of the sponsors to port you up a set.

Mike