Marc D

Hi I'm just wondering if anyone can help. I've got a 88 xr2 with a 1640cc Cvh with ported head, Newman phase 4 cam, weber 34 dmtr, Ashley race 4-2-1 manifold into Ashley 2.25" challenge single box system and lightened and balanced bottom end. It made 95bhp at the wheels. About 2 months ago I changed the gearbox and testing the lsd was working I missed 4th gear at 7k resulting in four bent exhaust valves. After taking it apart I found the 18 month old Newman cam was dead due to scoring on the cam bearings in the head and scored lifter bores. I found a spare lean burn head in the garage and sent it to Andrew at ALD to have ported and matched to the gaskets. I had new valves and guides fitted and 1.5mm larger inlets. Got a brand new Newman phase 4 cam and lifters and got it all run in and setup Monday. It ran alot smoother than it used to and idled and drove smoother however only made 81bhp at the wheels on the same dyno. We tried adjusting the timing and cam timing but 81 was the best he could get. He carried out a compression test and got 195,195,180 and 195psi. 3 is slightly down but not enough to worry about. I'm confused how I can lose 14bhp at the wheels with a better ported head and bigger inlet valves and a fresh cam. Could one or more of the rods be slightly bent due to hitting the valves? Or could my 34 dmtr be causing a slight restriction due to better flowing head? Bottom end was rebuilt last year in January and made 95bhp in February this year
Cheers for any help and sorry about the essay lol

mattxr3i

With all due respect, how do you know the porting is better than before - do you have flow stats for both heads. It has been proved a number of times that sometimes porting can cause a loss of power - I am not stating this is the case here though as I have heard good things about Andy's work.

Here are the things I would be looking at:
- Lean Burn head doesn't flow as well as hemi head (EFI is best out of all stock heads)
- Was the old head skimmed more than the new head therefore raising comp ratio
- Is the ignition system in good working order
- For the cam to be worn, maybe your oil pump is knackered and therefore friction is high

Cylinder 3 is a little concerning as it is just over a bar down compared to the rest, are the valves sitting right?

Johnny Knoxville

Was it dyno'd on different rollers?

Marc D

Was on same dyno. I haven't got flow stats from either head just on Andrews head you can see more material has been taken off as the path for the mixture is more direct. Both were lean burn heads as I have the lean burn pistons. The old head could have been skimmed a couple more times but wouldn't have thought it would make that much difference. The valves should be sitting right as they're all new as well as the guides and the seats were recut as the inlets are now 1.5mm larger. The oil pump is new, the cam was worn due to scoring in the lifter bores and cam bearings in the old head. Ignition system is spot on. New plugs, dizzy cap, rotor arm, newish splitfire leads and dizzy. Also drives and idles smoother than it used to although it doesn't rev as well as it used to

mattxr3i

Just because more material has been removed doesn't mean it will flow better. The speed of the air/fuel mist could be a lot less now and therefore the burn isn't so good.

There has to be a reason why cylinder number 3 is just over a bar less than the rest - could be headgasket (from cylinder to outside world), valve not seated right (seat or tappet issue) or a ring hasn't bedded in.

Next step would be a leak down test on cylinder 3 - air line is put into cylinder where sparkplug goes and you can tell what the issue is as the air escapes either from Inlet, Exhaust or Crankcase

mattxr3i

This may sound silly but, what have you done with the breather pipes?

Marc D

It has a bailey Rs turbo breather tank piped up as instructions. Might be worth doing the leak down test then. I was told number 3 being down isn't too much of a concern as its within 10% tho. I'm really hoping its bit down to the head work

pcbp97

are you sure its not just that transmission loss is greater on your newly fitted gearbox.

CrOwSoN15

95 seems like a low figure initially anyway?

Marc D

Old gearbox was knackered lol. Yeah I thought 95 was a touch low but driving it you would of thought it had loads more power. Andrew has said he will have a look at the head. Will see what happens with the leak down test then decide whether I should take the head off again

rsmark86

iTrader: (3)

sounds to me like the head isnt as good as what you had to start with

also i had a cam fitted by a so called professional and it was a tooth out and made about what your car was running lol

i had
wpe 1600cvh with newman phase 4 and twin 40s making nearly 160bhp at the flywheel

so only real difference was twin 40s and more compression

costina

iTrader: (1)

Timing is really crucial to theses engines. I had a pinto that gained 28 bhp by adjusting the pulley approx 1mm not sure in degrees and I thought I had it spot on..
95 at the wheels with say 30bhp trans loss 125@fly which isn't too bad stock efi is 108bhp and a cam will norm give you 12 to 15 bhp

CrOwSoN15

Bet that went well!

dug112y

iTrader: (1)

you say you tried adjusting timing/cam timing....are you measuring it properly or just fit and guess?? whats the fuelling situation/AFR?