OZHCR32

Hi people,

I have owned my 3dr for about 10 months and due to a freakish failure of an oil filter I have spun a bottom end bearing and am ripping the engine out this week for a rebuild.

As I have only had the car 10 months and most of my knowledge is of Nissans can people offer advice on the following:

What is the typical rule of thumb for the largest bore you can run on a 500hp setup before you have issues?

What is the general rule behind why everyone runs such low compression? In Australia I have access to 100RON pump fuel and/or E85 so looking at running around 9.0:1 compression but guess valve to piston clearance can arise as an issue.

As a general overview my engine is meant to be:

200 LONG STUDDED BLOCK
PERFORMANCE CAMS/VERNIER PULLEYS
PORTED HEAD


The engine is meant to be lots of things but guess I will know soon enough when i rip it down. It does run a Pectel T2 and T38 @ 28psi

opposite lock

iTrader: (3)

Its probably worth mentioning what the engine/car is intended for , race/road etc etc the engine can be suited to lots of different uses and hence different specs all together. There is some excellent advice on here but it,ll be difficult to advise best without knowing your intention with it.

OZHCR32

Sorry for lack of detail. Its a street car, I have a dedicated club/circuit R32 Skyline which is the impractical/fast car...so just want my Sierra to be a strong daily driver.



The above pic is the bus the engine is for. It The car is an 87 Sierra RS. It's suspension has been bushed with Koni Yellows, SCS 6 deg beam. Rebuilt T5, SCS built YB with 200 block, with Pectel T2 ECU, air injectors for boost control, SCS T38 and about 420hp. Runs 355mm 6 pot APs. So has the basic building blocks. The rest is a bit of a guessing match until i rip it down this weekend.

The main thing is the engine runs something like 7.4:1 compression. I would like to bump that up to around 8.5:1 and run about 25psi.

I would speak with SCS but now that me and the car are back in Australia going to have a got at it myself. Curious to know things like max bore for a 200 block without going to liners etc. Any off the shelf pistons with big enough fly cuts that allow you to run ~8.5:1 compression. The engine is meant to have headwork and cams but don't know the specifics of the cam lift. Will send them off next week to find the exact specs of duration and lift. Looking at them last week they have Ford logos on them so I guess that could mean they are std cams? It doesn't idle very angry and I think the head still have hydraulic lifters

So at present not looking at changing too much in the regards of head spec, cams or turbo (Unless it turns out that its all std) I have not terribly blown away/impressed by the T38 so considering changing the turbo to one of these http://store.forcedperformance.net/P...GT3076HTA.html

I should mention perhaps that Australian fuel its pretty easy to get 100RON fuel in my area so not scared to run some reasonable compression and boost.

botters

iTrader: (2)

the cams may have been reground mate, you dont HAVE to run low compression its just a lot do as this is the old school way of doing things and can ultimatley lose you response when off boost with modern fuel, turbo's and engine managment there is no need for lowered compression at all

OZHCR32

Thats my thinking re compression ratio. But when I spoke to a few people about YB engines they all seem to tell me that I cant run 8.5:1-9.0:1 compression ratios due to valve clearances etc. To which I reply well just run fly cut pistons and then I get all confused by the response and reasons for not being able to do it. Looking around this forum it does seem that the vast majority do all seem to run low compression in their builds so I dont want to go against the grain to only learn later why this is common practice. I expect given the motorpsort history of the YB head that the thing is effecient enough that it can handle decent cylinder pressures without pre-ignition.

Its a bit like who do YB engines rebuilt today have so much blow by? I am hoping to run tighter clearances and better rings etc in the hope that the thing isnt the oil burner it currently is.

opposite lock

iTrader: (3)

She,s a beauty mate nice one ! Is that an Austrialian cloud or UK one haha . The general way of thinking (not always) with a road engine is keeping the comp ratio standard or near it at 8:1. There are known engines that are above that level of compression for reasons i dont know really but response/driveability and off bosst performance can be improved by raising the ratio for instance. There must be lots of factors that determine it and when maybe good time to do this . Budget may also be a factor and ultimately what your after exactly. Big boost and high compression is definately doable with huge figures i think Rods YB is 8.5:1 massive boost but it isnt exactly your average road engine/car although can be used this way still .

OZHCR32

So started pulling the engine down today. This is the first YB I have had apart so can see that the head has had some porting, though I have no idea if its simply a clean up or rather something more comprehensive as I have not been able to find any decent pictures of std ports to compare to. It has some Mahle pistons and appears to have std rods with some sort of rod bolts (dont appear to be ARP)

So some questions....
1) BEARINGS - It also appears to have std Ford bearings. For general performance street applications is that the typical thing to do or is there a better aftermarket option for bearings available?

2) ROD BOLTS: Want to try and see what bolt they are to see how much they have yielded and guesstimate what the rods were previously torqued to. I ascertained they were around 50-60N.m from nipping them up before undoing them. Looking at the Ford manual that appears to be around std and since the bolts are stamped YB something I am guessing they are std rod bolts?!?!?! Do people use std FORD or do they go ARP for a 450-500hp build?

3) There is some discolouration in the crank. To me it looks like heat tint ?!?! Maybe its had a pretty big bottom end failure and the bluey tint is from excessive heat??? Or is this normal?

Some pics....





Anyone have any thoughts in the discolouration below?



Thankfully despite the bottom end knock the crank looks good




The no.1 bearing doesnt look too bad.



No.2 bearing shows some signs of damage...



No.3 bearing seems to be the main offender with No.4 looking much the same as no.1



Need to do a search and see what this model bearing equates to. If anyone knows then I keen to know.






Some general pics on inlet port...any idea if they are just tidied up or genuine porting?

opposite lock

iTrader: (3)

There,s a similar thread on at the moment about the cranks , goin by what a few have said the colouring is normal due to heat treating and your bearings appear to be the standard ford sizes although i could be wrong i,m certainly no engine expert just keen here. People are using the original bottom end engine parts for your power level this is common .
HTH
Try searching a few threads on here to gain more info and more importantly maybe see who can advise you best.

OZHCR32

So I plastigauged the healthy cylinder and it came out at 2.5thou. The spun bearing was 3 thou. Any idea what allowance i need to use for crush of new bearings? I think its time I just pull the crank out and measure it up and send it off for machining to suit some new undersized bearings. Was hoping to get away with using a new set of the same part no. bearings but I would really prefer to build the engine to 1 thou

opposite lock

iTrader: (3)

Should be plenty of advice on this . Have you spoke to scs who built the engine?

OZHCR32

Not recently. I am still hunting around getting the software and cable so that I can talk to the Pectel. Once that is sorted I will get back in touch to get the password, but have arranged to rip the crank out this weekend and will be getting it ground to suit some new bearings and going to get the big ends re-sized as well.

vroooom ptssssh

Discolouration on crank is normal.

Giving your access to 100RON fuel i'd go for Standard compression ratio, ofcourse this depends on what boost you will be running to achieve XYZ power? and if you run it on 100RON all the time or not.

OZHCR32

So does do the 205 and 200 blocks take the same sump gasket kits and thermostats?

I understand the 200 block that I have is from the later model 4x4s but I cant find any sump kits for a 4wd, only 2wd so am I safe in assuming they are the same? Ditto I am after an 83 deg thermostat but seem to only be able to find the 2wd thermo stat.

Thanks for your help...not many places locally can answer these questions and phone calls to the UK get expensive

opposite lock

iTrader: (3)

Burtonpower list bottom end gasket set http://www.burtonpower.com/sc794ak.html
MSD do an 82 stat for 4x4.