5 replies to this topic

[rosco 123]

Hi lads and ladies, long time peruser, first time posting.  I have to say I’m well impressed with the sheer amount of knowledge and expertise on here, it’s incredible! 
im about to get my grubby mits on a complete stock metro turbo engine and even after reading through this site for weeks now , I have a few questions.  First up obviously a strip down and review, after that some head work because of course and then crank balanced etc. The bores look excellent as do the original pistons, I guess ring’s are still a problem, yes? Funds won’t allow any turbo swaps but maybe an inter cooler though. Cams ?  I want to end up with a good strong road car with occasional track day fun. Over to the hive mind , thanks in advance 👍

[mini13]

okay....

rings are NLA for the original pistons, so the choices are a set of rings from total seal, or go +20, obviously see what the bores and pistons measure up like.

adding an Intercooler is a no brainer, just do it, practically anything is better than nothing.

Cam wise, the std one is fine, but a good upgrade is the N/A metro cam, dont go too hot cam wise on a turbo , you want to limit overlap, so also stay away from high lift rockers.  or anything over about 260 degrees unless your looking for mega power

apart from that, you want an X pin diff,

also bear in mind,ypu'll need a bulkhead box with the Metro turbo setup... a lot of eople flog them off and go down the Fusion fabs manifold with a GT17 so they dont have to chop the body.


 

[DeadSquare]

A good intercooler is money well spent.

 

It's probably best to stick with the standard cam,  even mildly hotter ones give the fuel consumption a nasty increase.

 

Pay attention to the cooling, supercharged engines burn more fuel, = more heat.

 

Sadly, superchargers don't like today's Octane ratings, so don't go mad with the compression ratio.

[rosco 123]

Hi , me again , I’m having some porting done on the (stock) turbo head and was wondering how much of a difference larger valves make? This isn’t an all singing and dancing screamer and if funds were plentiful then it would be a no brainier. At the moment it looks like I’ll be boring to 1293, balanced, intercooled, x pin, stock box maybe 3:1 drive, and tempted by the GT 1752 turbo or something  similar. I mean are we talking huge gains over the current stock valves? 
Also, is there a good alternative to the beautiful side mount turbo pipework of bagsport? 
The car to be a fun, summer use fast road and occasional track car, thanks in advance 👍

[Ethel]

There's not much difference in what works for forced induction compared to N.A.

 

As above, the exceptions are valve overlap & a bit more thought to heat. You can make up for less good flow with boost, but you have to get on boost first and it'll generate more charge heat to deal with. 

 

So, generally, improved flow is good. just don't go too extreme on valve sizes, cutting back guides... Cracked heads & burnt valves aren't inducive to performance.

[Turbo Phil]

The stock size exhaust valve is fine for all but the biggest output motors, but it’s definitely worth going to the bigger 35.6mm inlet.
Concentrate your porting efforts on the area directly above and below the valve seat. Cut the chamber walls back to deshroud the valves, cut multi angle seats and open the throats to suit the bigger inlets, then grind away the guide boss.
Then back cut the inlet valves (if you’re using stock, rather than the race type valves). This will give you the vast majority of the gains without even touching the ports.
It’s definitely worth improving head flow, more power on the same boost or the same power on less boost is a no brainer.


Phil.

Edited by Turbo Phil, 15 March 2024 - 06:51 PM.