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turbo 172 update (again)

Hi fellow nutters...

posted this to Chun below.. but copy here in case any of you guys with the parts missed it.

tried the parts on the 172 engine today (I now have a spare mk1 complete unit )

will be able to supply pics of what needs moving / removing.. its fairly minor. also, the front engine cover from the 172 can be re-used (Needs just one hole drilling and tapping in the new inlet manifold)

the head will need a slight porting session on the inlets.. only where the injectors point though.

considering not using the inlet adapter plate we discussed either ??.. might be better to drill the head (Its the same head casting as the turbo head and the locations are already there)- will have some pics of the manifold fitted soon and see which way you guys want to go ??.

will also have details of the oil feed and return as soon as I remove the 172 sump.. the feed will take the form of a tee piece in the oil pressure sender - will post details of the thred size / part number etc.

at some point, can you check your 172 fuel pump... it is located under the back seat.. a simple plastic clip on inspection cover needs to be removed to see the pump top.

have you all got 1 fuel pipe only going to the pump top??.. seems some mk1s had 2.. (ie - a return as well as feed)

(ps - you dont need to remove the pump.. just the inspection cover under the seat.. its a 2 minute job)


ps.. we can also do the oil feed from the location in the block where the genuine turbo unit fits. ??

it would mean removing gallery plugs to enable swarf clean out though ??.

do you want details for both methods ?.


Joe I think whatever you would think would be easiest, or better. Using the blank position would make the install more factory tho What do you other guys think?.


Hi Chun,

It would certainly be the neatest.

having to change the pistons means removing the engine anyways.. its a simple matter to strip the block and have it drilled / tapped / cleaned..

Also, whilst it is out.. the head HAS to come off to change the pistons.. might as well remove the vavles and lap them in.. at this point the head can be drilled / tapped, and ports opened out.

Some things worth doing when you get chance.

Exhaust manifiold (the turbo one).

get a genuine 172 exhaust gasket and mark the ports on the new manifold.

Have it gas flowed (I will ring Nick Hill for a price for all of us if ya like) - it only needs opening out about 1mm on the ports to suit the 172s slightly larger exhaust ports, then it would be useful to clean up the casting inside - a nice polish is not necessary, but good to start with.. more port matching and a wee bit of flowing.

I am working on the ali adapter to fit the 172 throttle body onto the inlet manifold.. the best way would be to remove the narrowing at the throttle body end of the manifold and have an ali pipe (about 2" long) welded to the inlet.. then a flange welded to that.. I am having the pipe(s) cut, and flanges machined.. the welding is probably the best bet as we can remove the slight restriction.. (The ali welding can be done locally) it will only be a few quid per manifold. will let ya know when the parts are ready..

will also get a group price from Nick to match / port n polish the inlet manifold.. this can be a high gloss finish with all rough edged removed. - the extra hole can be drilled and tapped at the same time.


Hi Joe,

Would be nice to have a group price with the exhaust manifold. So the acutal throttle body from the 172 will replace the one on the turbo manifold?, cool. I personally think if the engine has to come out for the pistons then tapping the blanks for the oil feed would be the best option to go. But i dont really mind, its up to you guys and Joe


yep, agreed, the throttlebody from the 172 will be the most appropriate by far.

and, yes, if you are going to do it,, do it right first time.

The other thing to note.. the gt turbo clutch plate appears to fit the 172 clutch, I am trying one this weekend, so no worries there (there are LOADS of upreated clutch plates for the 5gtt)



ClioSport Club Member
  E90 LCI 330d

As standard, an R5 GTT is -

Power - 120bhp @ 5,750rpm
Torque - 121lb/ft @ 3,750rpm
Weight - 830kg

So, decent power & torque in a car that weighs f*ck all = fast!

The clutch I have on my R5 GTT is good for 230+ bhp and 200+ lb/ft of torque. In fact, this clutch has been used on a couple of sub 13sec 1/4 mile GTTs, with no slip, so its good.

Thats not even a daft one, only a Group N 3-piece jobbie, you can get some serious clutchs for them!

this is an SBC I am considering to power the thing..

I love the idea of a gps card slot.. now that could be verrrrrrrrrrrry interesting...

add a PIC Microprocessor to drive injectors and ignition / act as tdc sensor missing pulse detector etc..

Program it in Delhi 6

hmmmmmmmmmm.. I always wanted me own engine management system.. think of what you could do with that lol... !!

traction control, security, gps nav, fuel injection and ignition, lama control both open and closed.. etc etc etc..

hmmmmmmmmmmmmmm again..



(This is for interest only - it will not affect your conversions at all)

- the turbo block has now been examined, and there are subtle differences to the 172, the water pump for one.. is competely different.. far smaller on the turbo block - not less efficient - just far smaller

the flywheel and clutch is about 1.5 inches in diameter greater than the 172, looks like the diesel clutch, also got a shock abosrber built in.

the oil pump is slightly higher psi, but it only takes a small metal washer to alter the 172 one

The gearbox bellhousing mount is obviously bigger to accomodate the larger (and heavier !) flywheel. but now the mating face will fit the PK6-003 6 speed box !!.

crank has a different part number.. still investigating this.. could be a different grade of steel or forging.. oooooooo .. nice..

rods are the same...

valve sizes are the same

head is slightly worked on the first inch only of the inlet ports on the 172, the 172 exhaust ports are about 1mm larger.

Head volume appears identical but havent had the pipette out yet ...

Sump is larger capacity on the turbo as standard, there seems to be more emphasis on the bracing in the sump construction.

both engines have the oil spray pipes into the lower part of the bore and under the piston.. bloody excellent mr reno !!.

rear engine mount on turbo block only lines up to 2 holes on the 172 mounting (out of 3).. so not really an issue with a brace plate to another hole present on the turbo block.

cam timing.. havent had time to check yet...

turbo unit has no vvt..

cam wheels on the turbo are a 10th the wieght of 172 ones !!!!!!!!!!

yes, seriously, the 172 cam wheels are 10 times the weight.. .. this is due to the use of the VVT phase shifter and also the corresponding rubeerised shock mount on the exhaust wheel..

still not convinced about this vvt mularky lol !.

might have a set of the turbo cams reprofiled to something I have yet to decide lol...

Might consider the turbo block and 6 speed - or even diesel box in mine... ??
the oiler box would be a great turbo box !. (And could accomodate the big clutch.. the flywheel would HAVE to be lightened though... )

just musing..

How much power can the diesel box take Capt?. And how much would a diesel box be? Can you provide me with ratio info for the diesel box?.



Hi Chun.... no is the simple answer lol

the diesel box can certainly take the torque, revs are not really an issue.

if the diesel box IS stronger, then kewl.. but the simple answer is... I THINK it will be, but I dont know yet

ratios........ soon young Skywalker... soon.....

I have to rest sometime lol...


Chun. LMAO !! nice one !

the six speed is as much as the six speed ??????

poooooooooooooof.. head exploded dood ??

Mathew, I cant find a box (that I can get at the right price ) that will fit the standard 172...

so to go to a sixer at the mo would seem to require the turbo block...