Skimming the Block to Raise Compression

[Sonic Boom]

Attemping to build an uber cheap 197 engine into a 172 block, new high comp pistons is not a option in fact no upgrade parts of any description will be added apart from brand new gaskets and the head will be stripped and fitted with new valve stem seals.
I understand head skimming is a bit of a no no, so thought if we could raise the compression by skimming the block?
We have all the machine equipment available and could even pocket the pistons further for extra valve clearance if required.
I know this is done in other engine application but in short is there any specific reason(s) why this would be a no go in a F4R engine?
Cheers Rich

 

[bloke]

you're putting 197 pistons in a 172 block?

 

[Sonic Boom]

you're putting 197 pistons in a 172 block?

Yes building the whole 197 engine into 172 block.

Rich

 

[bloke]

fwir 197 pistons are higher comp than 172/182, 197 head has slightly bigger chamber so if you run the pistons with a stock 172/182 had you'll be up on compression anyway.

not sure on clearance though so you'd have to check into that though. i'm planning on chucking a set of 197 pistons in my phase 1 at some point just to see how much more we can squeeze out of it.

also i've heard contradicting things about crank weights, 197/200 is meant to be lighter than 172/182 but also heard it's the same apart from the phase 1 172 that's the lightest one.

 

[marinemackay2003]

Iirc you need to watch you don't go to far
Something to do with not being able to achieve the correct cambelt tension

 

[bozothenutter]

ask Mark @NorthloopCup

 

[Sonic Boom]

fwir 197 pistons are higher comp than 172/182, 197 head has slightly bigger chamber so if you run the pistons with a stock 172/182 had you'll be up on compression anyway.

not sure on clearance though so you'd have to check into that though. i'm planning on chucking a set of 197 pistons in my phase 1 at some point just to see how much more we can squeeze out of it.

also i've heard contradicting things about crank weights, 197/200 is meant to be lighter than 172/182 but also heard it's the same apart from the phase 1 172 that's the lightest one.

Interesting about the crank weights I take it we are talking a couple of grams thou?
My current engine is Ph1 so I could weigh them both although I don't think I have anything accurate enough.

Rich

 

[bloke]

will ask nick at pms when i speak to him next.

what head you using?

 

[Sonic Boom]

will ask nick at pms when i speak to him next.

what head you using?

It's a complete 197 transfer into a 172 block.

Rich

 

[bloke]

pain to use the 197 head fwir? need to drill oilways as the dephaser is ran differently. 172/182 it's either on/off but 197/200 is fully variable.

what ecu?

 

[Sonic Boom]

Where do you need to drill holes?
Hopefully using the 197 ECU too, this is a proper budget conversion.

Rich

 

[bloke]

don't know, not looked into it that much to be honest, think that's how mark has done it though?

 

[Chambers_RS]

I'm doing this. Currently in the process of stripping down a 200 engine so might be able to tell you the crank weights as I've got 172 engine stripped.

Think you will have to use the 172 head tho for sure. And it won't be a budget build I don't think lol

This guy has done it too
http://cliosport.net/threads/my-little-rb-182-team.807262/

 

[NorthloopCup]

The early ph1 cranks are what you need as they're the heaviest and according to form the strongest.
197/200 is the next one down in terms of weight, but it's been balanced from the factory to withstand 7800rpm.

172 ph2 crank is the lightest and wankest one. You only have to compare the design to see why, and the 182 crank weighs in at somewhere between the 172 ph2 and the 197/200.

 

[NorthloopCup]

don't know, not looked into it that much to be honest, think that's how mark has done it though?

I ran the 197 head on mine and ran the fully variable vvt on the gen90. No oilways redrilled at all. I've looked at all the oilways on the 1*2 and the 197 head, and there's no requirement to drill oilways. You just need to sort the dephaser solenoid.

 

[T.Trophy]

I think the drilling that has been mentioned is regarding the pulley set up.

As we know the 197 f4r and f4rt engines have the water pump running from the cambelt, the clio 1*2 f4r uses the aux belt and needs an additional pulley to compensate. It's easy enough to compare the two heads to see where you need to drill and tap a hole for the extra idler pully.

As for clearance you should be fine using the 197 pistons as they have large valve pockets cut as they use pretty wild cams.

As Mark has mentioned there is no need to do any oilway work, 172 vvt is switched and the 197 vvt is ran with PWM. You just need the correct solenoid and an ecu capable of running PWM vvt control.

 

[bloke]

I ran the 197 head on mine and ran the fully variable vvt on the gen90. No oilways redrilled at all. I've looked at all the oilways on the 1*2 and the 197 head, and there's no requirement to drill oilways. You just need to sort the dephaser solenoid.

wonder what i was thinking of then? i blame the bump to my head still :wink:

 

[Chambers_RS]

I'd just use the 172 head. Especially if it's going to be a budget build.

Could go for wild cams and vvt delete?!

 

[Sonic Boom]

The early ph1 cranks are what you need as they're the heaviest and according to form the strongest.
197/200 is the next one down in terms of weight, but it's been balanced from the factory to withstand 7800rpm.

172 ph2 crank is the lightest and wankest one. You only have to compare the design to see why, and the 182 crank weighs in at somewhere between the 172 ph2 and the 197/200.

I ran the 197 head on mine and ran the fully variable vvt on the gen90. No oilways redrilled at all. I've looked at all the oilways on the 1*2 and the 197 head, and there's no requirement to drill oilways. You just need to sort the dephaser solenoid.

Cheers Mark can I give you a bell when I start trying to bolt it all together if I need any help?

Cheers Rich

 

[Sonic Boom]

I'd just use the 172 head. Especially if it's going to be a budget build.

Could go for wild cams and vvt delete?!

I'm hoping to use the 197 ECU and engine harness I already have, just need to see if it can be married up to my Ph1.

Rich

 

[NorthloopCup]

Cheers Mark can I give you a bell when I start trying to bolt it all together if I need any help?

Cheers Rich

Yes no problem mate.

 

[rmfisher18]

Hi,
Sorry to hi-jack but I have been looking at a similar route to build a rally car engine (more focused on mid range torque rather than top end power).
Can anyone confirm that 197 pistons will fit in an otherwise standard 172 engine? and if so what does it lift the compression ratio to?
I will be using catcam 438's so valve lift is same as standard...
Many thanks!

 

[powerclio]

anybody has a working 200 head in a 172 block? im struggling with VVT now. I want to use a 200 dephaser but I have a 172 ecu. Is possible?

 

[NorthloopCup]

anybody has a working 200 head in a 172 block? im struggling with VVT now. I want to use a 200 dephaser but I have a 172 ecu. Is possible?

Not if you want it to be constantly variable. All the 172 ecu can do is on/off.

 

[Sonic Boom]

Ah I remember starting this thread in the days where I thought I could do Motor Racing cheaply!
Now look at me lol

Rich

 

[NorthloopCup]

Ah I remember starting this thread in the days where I thought I could do Motor Racing cheaply!
Now look at me lol

View attachment 1486447

Rich

😂😂😂😂

 

[powerclio]

Not if you want it to be constantly variable. All the 172 ecu can do is on/off.

can i use the 197 dephaser and vvt solenoid but switching only on and off?

 

[NorthloopCup]

can i use the 197 dephaser and vvt solenoid but switching only on and off?

Oilways in the head for the 197 are different for the dephaser. You need to be careful as you get more advance with the 197 dephaser than the 172

 

[powerclio]

Oilways in the head for the 197 are different for the dephaser. You need to be careful as you get more advance with the 197 dephaser than the 172

But i read in this forum that you can use the 172 dephaser and solenoid but you have to invert the way vvt solenoid is activated, that's true?

I don't know what is the best alternative to use the vvt in the 197 head with 172 block configuration. Did you change the ecu? i just want to keep my ecu and use 197 dephaser and solenoid but i don't know what will happen if the advance of the vvt is more aggressive...

 

[NorthloopCup]

But i read in this forum that you can use the 172 dephaser and solenoid but you have to invert the way vvt solenoid is activated, that's true?

I don't know what is the best alternative to use the vvt in the 197 head with 172 block configuration. Did you change the ecu? i just want to keep my ecu and use 197 dephaser and solenoid but i don't know what will happen if the advance of the vvt is more aggressive...

I think it can be done yeah, but I ran the full vvt so can’t say for definite.

 

[powerclio]

I think it can be done yeah, but I ran the full vvt so can’t say for definite.

Maybe the best solution is run 197 vvt solenoid and 172 dephaser ? the oil drills will be the correct and the ecu will shift on and off the solenoid, doesn't sound logic?

 

[NorthloopCup]

Maybe the best solution is run 197 vvt solenoid and 172 dephaser ? the oil drills will be the correct and the ecu will shift on and off the solenoid, doesn't sound logic?

All you can do is try it mate