Tuning a 2.25 petrol

Hi, I am currently in the process of tuning a 2.25 petrol, its for my trialer that im going to race next year but that besides, it may be of interest to someone.

I am running LPG on the engine, which we think has given it a bit of a boost anyway (or maybe it was just the **** carb on it before was letting it down)


I picked up an engine advertised in the free ads for a tenner , its a 5 bearing run of the mill 2.25 petrol, on strip down we found its been rebuilt before but thats not really important.

The first step was to strip the ancillaries off until we had just the block and head, then the head was ground by 2mm and polished and ported the ports. the block has been re-bored 40 thou, new pistons, the high torque kent cam arrived last week. I cant get any reasonable priced 4 branch manifolds, so going to cut up some old manifolds and make our own.

Aiming for around 120 hp, though maybe thats optimistic? so would be happy with 100, coupled with the torque increase, it should be good.

just need to bolt it back together now

120 might be a bit optimistic. Are you going to be running on road much or just trialling?

Have you looked at ACR they do an SU carb kit and replacement 4:1 one manifolds

I put a DMTL weber and defender manifolds on which is great as it has the progressive barrels so good control of low down torque or put your foot down and get both barrels. I bought a new one from fastroadcars.com I also got a wideband lambda sensor for tuning but it didn't need much I just dropped one size of idle jet (for efficiency) but if I was trialling I'd probably leave it running a touch rich.

The main thing is getting the cam timed in and get higher torque - it makes a huge difference to driveability you can trundle up hills in 4th that before would require revving the cock off it in 2nd...change to 3rd, run out of steam, repeat...

If you're spending all that time and effort I'd ditch/flog the LPG and use the money for full-fat petrol (i.e. 97/98). No matter what you do you have to compromise the setup for LPG and all the gubbins bugger up air flow, plus with decent petrol you can run a good 4-5 more degrees of advance.

One thing I did find out was not to try running the vacuum advance straight from the manifold it ruined engine breaking, instead run it from the ported vacuum on the carb if you can. It will pop and fart going down hills a bit more but engine breaking seemed to be better...

You lucky git. I've been keeping an eye out for a 5mb block for a while...

Just trialling, and racing.

I really want to stick with the lpg, its off of a forklift that used a rover engine , it just has so much torque compared to standard, even webber. At the last trial the 2.25 was still pulling at the top of a hillclimb where a v8 ran out of power! It also means it runs on any angle.

I have seen acr, and while its great i got the high torque cam from kent cams for £60 so okay, its been re profiled as opposed to having a new cam, but it should increase the torque and hp plenty

fair enough about LPG - for ACR I meant they do fanimolds...I'm not sure how much difference they make though, let me know if it makes a big difference as I'm half tempted to make something myself...