compression issues.
08-06-2009, 05:19 PM
#4
Had the head skimmed on an engine rebuild and i think its had a fair bit taken off. So now its all put back together its pinging a hell of a lot. Been through every possibility of it being running and fueling issues and even still on tesco 99 its still pinging.
Had it diagnosed the other day and they reckon its more than likely the compression ratio on the std pistons after the heads been skimmed.
Had it diagnosed the other day and they reckon its more than likely the compression ratio on the std pistons after the heads been skimmed.
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08-06-2009, 05:40 PM
#8
yeah 1.6 cvh yeah.
Well ive been told that pinging engines can be a sign of a higher compression ratio. I think the head thats on my engine now has been skimmed twice. So im guessing that could be accounting for the compression issue?
Well ive been told that pinging engines can be a sign of a higher compression ratio. I think the head thats on my engine now has been skimmed twice. So im guessing that could be accounting for the compression issue?
08-06-2009, 06:36 PM
#10
A setup will sort that out, or if you want to do something now to save an engine then retard the timing to 8degrees BTDC (if it's not already), run V-Power 99RON, and turn the boost down a couple of psi!
Why do you think it's Det'ing?
As far as skimming pistons, or decomp plate i'd do neither!
Skimming stock RS pistons will just reduce what BHP they can take and a decomp plate will alter the shape and size of the 'squish' area and as a result your burn pattern which if your really unlucky could actually increase the chances of Det!
08-06-2009, 06:55 PM
#11
Well this issue occured on the rollers whilst being set up.
and it just got worse and worse to the point where the timing was retarded right back and the boost knocked off. Yet its still det'ing at around 6psi.
At first I thought it was a fueling issue, but after renewing the whole fuel system the problem is still there.
and it just got worse and worse to the point where the timing was retarded right back and the boost knocked off. Yet its still det'ing at around 6psi.
At first I thought it was a fueling issue, but after renewing the whole fuel system the problem is still there.
08-06-2009, 07:16 PM
#13
Well this issue occured on the rollers whilst being set up.
and it just got worse and worse to the point where the timing was retarded right back and the boost knocked off. Yet its still det'ing at around 6psi.
At first I thought it was a fueling issue, but after renewing the whole fuel system the problem is still there.
and it just got worse and worse to the point where the timing was retarded right back and the boost knocked off. Yet its still det'ing at around 6psi.
At first I thought it was a fueling issue, but after renewing the whole fuel system the problem is still there.
Must be a fuelling problem surely?! Did you renew with all new parts or second hand?
Unless your compression really is that high?? Have you done a comp test? Freshly built RS should be about 175psi (12bar) across all 4, plugs out, WOT, warm engine, 10sec crank.
If it comes back at like 200psi+ then at least your know?!
08-06-2009, 11:32 PM
#14
well thats what i thought,
brand new pistons, freshly honed bores, band new rings. all points towards a nice bit of compression. However, if the head has been skimmed twice, you could be talking 1-2mm difference.
getting a comp test done in the week, so see what happens.
brand new pistons, freshly honed bores, band new rings. all points towards a nice bit of compression. However, if the head has been skimmed twice, you could be talking 1-2mm difference.
getting a comp test done in the week, so see what happens.
Last edited by Chopshop85; 08-06-2009 at 11:45 PM.
09-06-2009, 12:07 AM
#15
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Mmm would really need to know the measurements i.e how much exactly has been taken off the head....pity you hadn't measured the c/r when building it if it's had that much taken off the head. The reason i say this is because you can run pretty big bhp on standard c/r and higher c/r's too, mine was running 245bhp with no detting issues on standard c/r pistons with a head that had been skimmed a couple of times (1.5 bar boost) so if the engine's fine i'm sure someone who knows what they're doing could set it up ok. If you need to lower the c/r slightly you could always take a bit out of the head (the bowls) instead of skimming pistons, would need to be done accuratly though etc but i wouldn't be too sure that's your problem, especialy if it's still detting running such low boost......
Last edited by rstdave; 09-06-2009 at 01:14 AM.
09-06-2009, 12:29 AM
#16
The car was set up at northampton motorsport.
The car made 160bhp on its old engine no bother. Until the big ends became worn which is why its had a rebuild. Also nothing has been changed on this new engine except for a better coil and some leads.
Also a c/r test is about the only thing i havent done. lol
I mean onto the list of things that im now going to try is a new metering unit off a 200bhp engine (as mine has never seen larger ammounts of power), get the injectors tested and go for a compression test as well. Going for the process of illimination! lol
at least this way everything will be sweet. touch wood.
The car made 160bhp on its old engine no bother. Until the big ends became worn which is why its had a rebuild. Also nothing has been changed on this new engine except for a better coil and some leads.
Also a c/r test is about the only thing i havent done. lol
I mean onto the list of things that im now going to try is a new metering unit off a 200bhp engine (as mine has never seen larger ammounts of power), get the injectors tested and go for a compression test as well. Going for the process of illimination! lol
at least this way everything will be sweet. touch wood.
09-06-2009, 06:44 AM
#17
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dont be thinking that you can do a compression test and find out what cr your engine is because you cant. you would need to take the head off and measure it. and there also aint a squish area on the cvh, but saying that you still dont want a decomp plate.
09-06-2009, 07:22 AM
#18
I thought the squish area was the space left above when the piston is at TDC and so it applies to every engine, is that not right?
10-06-2009, 12:54 AM
#23
Like low comp pistons are ŁŁŁ's and these decomp plates are Ł30! sounds to good to be true, wondered if anyone had ever had an success with them.
Got a comp test lined up this week to see what comp the chambers are making see if its a bit high or not.
New metering unit and getting my injectors tested as well incase its a fueling issue instead.
Im just a tad confused, the car used to run sweet before the engine rebuild, now its just gone to shit lol
10-06-2009, 01:05 AM
#24
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sounds like maybe the metering head has died m8,like u said a new one might sort it.everyone knows mfi is unreliable,thats why i wanna go efi with mine and ive took it off the road
10-06-2009, 02:05 AM
#26
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lol yea ur runnin the same specish as mine,but mine needed to come of the road,an thats were its staying now until its done.thousands of ŁŁŁŁss later though.like urs alot m8,nice wheels,i love white wheels
10-06-2009, 02:11 AM
#27
thanks man. it doesnt look to great in the flesh, the old red paint is starting to look a bit tired.
but at the moment its "power not paint!" as a friend put.
Well its been off the road now for a few weeks while i did the sump gasket twice! as is the case with the cvh. Then went to start it again and it wouldnt idle. Somehow whilst doing the sump gasket my brake servo had split!! (gotta love these old cars) then with the whole det thing getting worse and worse I'm starting to lose hope.
Came so close to getting rid of it last week after the tools went flying across the yard for the 1000th time! 3 years ive had it, and i just want it to work :'( lol
But i keep saying to myself, what would i get to replace it, and the fact ive just spent ŁŁŁŁ's on the engine rebuild, new suspension etc... it just seems silly to give up.
but at the moment its "power not paint!" as a friend put.
Well its been off the road now for a few weeks while i did the sump gasket twice! as is the case with the cvh. Then went to start it again and it wouldnt idle. Somehow whilst doing the sump gasket my brake servo had split!! (gotta love these old cars) then with the whole det thing getting worse and worse I'm starting to lose hope.
Came so close to getting rid of it last week after the tools went flying across the yard for the 1000th time! 3 years ive had it, and i just want it to work :'( lol
But i keep saying to myself, what would i get to replace it, and the fact ive just spent ŁŁŁŁ's on the engine rebuild, new suspension etc... it just seems silly to give up.
10-06-2009, 02:18 AM
#28
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too fcukin rite dont give up man,uve had it 3years and spent loads on it,bet wen it works u love it.ive driven mine 3 times at about 10 mins a time and then it got put away,but i love it,love when it comes on boost an how quick it feels.ive only just started on my project really but i know its gonna cost me bout 20k but wouldnt wanna spend it on anuva car,thats fo sure,dont give up m8.
10-06-2009, 06:23 AM
#29
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What I think:
1.
Skimming the head twice hardly makes over 1mm difference to original.
2.
If the head has been overly skimmed, the easiest remedy is another head.
3.
Even standard carb CVHs with the 9.5:1 CR run over a bar of boost easily with a large front mount IC.
4.
Decomp plate would be my last choice for this.
5.
The original pistons have 7mm of material on their crown. Taking 1mm from the center is perfectly ok. (Don't reduce the distance from the crown to the first piston ring, so only a bowl in the center)
6.
During the setup, surely the AFR was recorded?
7.
Check your plugs. Is it a problem with only one cylinder?
8.
Running a large front mount IC and 15 psi of boost, I would personally like to have a compression higher than standard. If the engine can't handle it, you have a problem somewhere.
9.
Do the compression test.
10.
Have you checked that the ESC-II ecu is doing it's job at adjusting timing with the MAP reading.
11.
You do have the MAP hose connected, do you?
12.
You can measure the head total thickness even when it's on the engine. Compare that to standard or guideline value from manual.
1.
Skimming the head twice hardly makes over 1mm difference to original.
2.
If the head has been overly skimmed, the easiest remedy is another head.
3.
Even standard carb CVHs with the 9.5:1 CR run over a bar of boost easily with a large front mount IC.
4.
Decomp plate would be my last choice for this.
5.
The original pistons have 7mm of material on their crown. Taking 1mm from the center is perfectly ok. (Don't reduce the distance from the crown to the first piston ring, so only a bowl in the center)
6.
During the setup, surely the AFR was recorded?
7.
Check your plugs. Is it a problem with only one cylinder?
8.
Running a large front mount IC and 15 psi of boost, I would personally like to have a compression higher than standard. If the engine can't handle it, you have a problem somewhere.
9.
Do the compression test.
10.
Have you checked that the ESC-II ecu is doing it's job at adjusting timing with the MAP reading.
11.
You do have the MAP hose connected, do you?
12.
You can measure the head total thickness even when it's on the engine. Compare that to standard or guideline value from manual.
10-06-2009, 10:40 AM
#33
Well my metering unit came today, and tbh.. im not happy. Its is a right state, there is no idle screw and its a series 1 metering unit.
is there any difference between the series 1 and 2 metering units, other than the position of the fuel lines?
is there any difference between the series 1 and 2 metering units, other than the position of the fuel lines?
10-06-2009, 10:46 AM
#34
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S2 has an aluminum bottom section that has separate locations for the boost control valve return air hose and the crankcase breather hose.
S1 version has a plastic bottom section, more travel for the air flap, and only one location for breather hose. The boost control hose is T-ed together earlier.
S1 version has a plastic bottom section, more travel for the air flap, and only one location for breather hose. The boost control hose is T-ed together earlier.
10-06-2009, 11:47 AM
#35
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ah m8,savage,sounds like it wont work.check in the rs turbo for sale parts there was a guy selling 3 rs turbo metering heads cheap,an they looked mint
