Engine build advice please

[Spesh 31 1 Cars]

that seems like a reasonable reason to spend a little extra, thanks

[Spesh 31 1 Cars]

Next question

 

Valve springs.  They seem to vary from expensive to eyewateringly so.

 

Any suggestions/advice on which to use?

 

11.7 lift and 7500 limit

[welshpug 1,657]

I'm using piper cams double springs  in mine, they fit the standard retainers, install height in my head was bang on after it had the 3 angle seats done.

 

They're  the same spring in the coscast Vauxhall and the cossie turbo engine as well as both xu10 16v engines.

[Spesh 31 1 Cars]

2 hours ago, welshpug said:

I'm using piper cams double springs  in mine, they fit the standard retainers, install height in my head was bang on after it had the 3 angle seats done.

 

They're  the same spring in the coscast Vauxhall and the cossie turbo engine as well as both xu10 16v engines.

Interesting, I assume theres no real need to do the retainers unless your going silly RPM?  and you wouldn't happen to have access to the part number of them please?  I'd appreciate it alot

[petert 586]

I use a single spring from PAC for that application, PAC-S10011 and matching titanium retainers 99333. Available from Catcams, Pug1off etc. They also fit the standard retainer but you need approx. 2mm of shim to get the seat pressure correct.

 

For 8000+ I use K20A double springs SPR-H1021D, from Supertech and Z900 titanium retainers.

 

Regardless of what you choose, make sure you confirm the seat pressure is 90lbs. A useful resource is the 1mm shim, 095131.

[Spesh 31 1 Cars]

20 hours ago, petert said:

I use a single spring from PAC for that application, PAC-S10011 and matching titanium retainers 99333. Available from Catcams, Pug1off etc. They also fit the standard retainer but you need approx. 2mm of shim to get the seat pressure correct.

  

For 8000+ I use K20A double springs SPR-H1021D, from Supertech and Z900 titanium retainers.

 

Regardless of what you choose, make sure you confirm the seat pressure is 90lbs. A useful resource is the 1mm shim, 095131.

Thanks Peter.

 

https://www.peugeot-tuning-parts.co.uk/peugeot-405-mi16-cat-cams-valve-springs-retainers  They are listed for mi16 but I assume they will fit a gti6 head ok?

 

Also the shim part number, what manufacturer? I think it would be prudent to get a set in just in case.

[petert 586]

Sorry, I thought we were talking Mi16 heads. If GTI6, I’d just set them up with 90lbs of seat pressure and send it.

[Spesh 31 1 Cars]

I have the short block pretty much built up now, waiting for cams etc to arrive to do some final clearance measurements for the valves.

 

After remeasuring this is what I have

 

87mm Bore

92mm Stroke

158mm rod length

65abdc valve close

36.1cc head chamber

9.1cc piston volume at tdc

1.2mm gasket thickness.

 

Static CR of 11.43

Dynamic CR of 8.84

 

I think thats looking ok?

 

 

I also have (yet another!) question on Head gaskets.  Will I have to go to an 88mm head gasket for this?  I've got a stock (think its payen) gasket here that measures at 87mm (as accurately as I can measure with calipers) and there is no noticable overhang,  however it does feel to be right on the edge.  will this suffice?  I don't mind getting an 88mm gasket if its needed, would also give me the option of changing the thickness a little to adjust the CR if anyone thinks its needed.

 

Edited December 14, 2022 by Spesh
typo

[petert 586]

If you're confident the ring is not intruding, I'd run with it. I normally add 0.5mm to the bore.

[welshpug 1,657]

standard oem gasket worked for mine

 

20160522_162709 by WELSHPUG, on Flickr

[Spesh 31 1 Cars]

Almost there with parts to finish the build but, predictably, I have another question.

 

Exhaust manifold and what to use.

 

I've got a 2.5 system from downpipe back but am currently on the stock gti6 manifold. From a bit of reading around this seems borderline given my spec.

 

I'm not averse to making my own, however there doesn't seem to be much info out there on runner sizes/lengths.

 

The maniflow seems to be the most recommended but only seem to be available in mild, I'd rather keep it all stainless.

 

I've seen mention of turning the original manfiold into a 421 too?

[petert 586]

I run a GTi6 manifold and 2.5" system and it makes 148kW at the wheels. Would it make more with bigger pipes? Possibly. When you get to that level I'd start worrying. There are more important things to get correct in the tune.

 

There are plenty of online calculators, which will suggest you should probably have 1.75" primaries rather than 1.625". eg

http://www.mezporting.com/exhaust_length.html

 

 

[Spesh 31 1 Cars]

PXL_20230222_200019176 by Mark Needs, on Flickr

 

Timed it up yesterday, set the inlet to 105atdc and the exhaust at the suggested 108btdc

 

Got a minor issue with a rod bolt just grazing the windage tray underneath the oil pump spacer plate so need to address that and then it's pretty much ready to go