Tuning a high milage engine

[nathanH]

What checks would I need to do if I was to start tuning my 96k ph1 172 engine? Since ownership I have changed the oil every 10k and used 98 Ron fuel when I can. Checks I can think of doing off the top of my head would be:

Cold and Hot oil pressure tests and a compression test.

I had the car rolling roaded at a CS Hill power meet ages ago and it made 158bhp atw or something like that. car is 100% standard.
Im contemplating the bolt on ITB kits from either KTR or GDI.

Nathan

 

[Icarus]

As long as it is making good, equal compression over all four and showing decent oil pressure it should be fine.

Pauls supercharged one is on 100K miles and kicking out 296bhp and my 100K mile knacker of an engine with low compression on two cyls is still making 184bhp.

It does depend what you mean by tuning though. If you mean a different induction/filtration setup and an exhaust then it'll make no odds either way. If you are considering cams, headwork, inlet manifold changes etc. etc. then you may well end up rebuilding the top end etc. anyway.

Cheers
M

 

[stan*]

A leak down test would give you a far better indication of engine condition than a compression test.

I would at least remove the head and have valve seats freshened up, and valves cut back and lapped back in.
Better still is also remove pistons, hone bores, and fit new rings.

Just depends how far you want to go, how much effort you want to put in, and what gains you want to see.

 

[nathanH]

how would I conduct a leak down test? Dont think i would want to go as far as removing the head.

 

[Bazzon]

We put our ITBs on a 87K PH1 engine.

We have broken 1 gearbox though but that was before the ITBs when it was running 190Bhp from CAMs. got a reconed box in now and running over 200BHP seems good.

Our car only gets used on track so takes a hammering 95% of the time.

 

[stan*]

how would I conduct a leak down test? Dont think i would want to go as far as removing the head.

With a leakdown tester (without sounding like a t**t!)

Basically the cylinders are pressurised with compressed air, and percentage leakage is measured. You can then isolate leakage by physically listening for where its coming from...either past rings, past inlets or past exhaust valves..

If you have the capabilities, its definately worth re-sealing the valves..

 

[Fletcher]

I was thinking about putting some itb's on my 172, it's now done 98k.

k-tec don't really think the mileage should be a issue, if the engine has been looked after.

 

[Laura]

Jons 172 is on 100k nowvon itbs

 

[Waitey]

My old MX5 was one 100k and it was running 15psi though a std engine. 150bhp over the standard output of 90bhp and it was fine.

 

[Russ_16v]

mines 124,500 miles, amd made 173.3 bhp with just a stainless exhaust. Iv always been the 'if it aint broke dont fix it' kinda way so to be honest have a few basic checks done and as long is it seems ok and the enfine seems healthy i wouldnt worry

but it does depend on what you mean by modding, as it could work out cheaper to buy another engine and build that up, get it fitted and offset the cost by selling yours

 

[nathanH]

Just ITB's for now.

If I was to ITB I was planning on removing the engine, fitting a new a waterpump, aux/tensioner and probably a new cam belt (belt was only changed 2 years ago tho) and fit a new clutch for good measure as the original is on 96k... and probably lighten the fly wheel.

sorry, wondered what a leak down envolved.

 

[stan*]

It may be "fine", no-ones disputing that.

Theres a difference between "fine" and "spot on" however...

As I said, it depends how far YOU want to go, and how much effort you want to put in.

 

[sideways danny]

my take on it is, if there's nothing actually "wrong" ie noticable, or detectable with a compression test then go ahead, but keep in mind you may have to do some work in the not too distant future. You have to take into account that it's a road car and not a race car, so every last half hp isn't that critical

 

[Russ_16v]

It may be "fine", no-ones disputing that.

Theres a difference between "fine" and "spot on" however...

As I said, it depends how far YOU want to go, and how much effort you want to put in.

my take on it is, if there's nothing actually "wrong" ie noticable, or detectable with a compression test then go ahead, but keep in mind you may have to do some work in the not too distant future. You have to take into account that it's a road car and not a race car, so every last half hp isn't that critical

two very good points here mate, there is no point in spending out on something that doesn't need doing, but it all depends on your budget i would say

 

[stan*]

again it depends on your interpretation of "doesnt need doing".

I can pretty much guarantee if you do a leak down test it will show leakage past the valves. It may be fine, but its not 100percent right.
Depends how anal you are I guess....

Road car or race car...I like everything to be as perfect as possible

 

[Russ_16v]

again it depends on your interpretation of "doesnt need doing".

I can pretty much guarantee if you do a leak down test it will show leakage past the valves. It may be fine, but its not 100percent right.
Depends how anal you are I guess....

Road car or race car...I like everything to be as perfect as possible

Ok maybe i better illiterate a bit more, by saying doesnt need doing i mearly mean the engine may produce good power without the need of a strip, i know you know a million times more than me here chap so i should have explained better, as you have said there will always be improvement to me made, i was trying to say that for the money he might have to spend he may not go down that route

 

[stan*]

yeah I agree..thats why I said within his own ability...i.e on the cheap.
If you've got to pay someone to do it, then yes it isnt worth it unless leakage is serious...

 

[Andyman]

At the end of the day whats modding going to do? Accelerate damage thats already showing at the very worst.

Depending on the mods, if the engine does expire the mods will still be in tact and the money that would be spent stripping it down and checking prior to modding could be spent replacement parts if the very worst did happen. - You could spend a bomb checking the box too, replacing the clutch, drive shafts, potential worn bushes etc etc etc if you wanted to be 110% safe. - but why bother if its only a road car and theres no signs of probs?

I'd put the car on the rollers. If their happy with the way its running then mod away

Just my opinion