City Modding questions

[Bino]

I've done a few searches for this information and didn't really pan out to anything, so here we go.

I did a search for Turbo upgrades and didn't come up with much.  Seems like a Garrett GTBB15 (or IHI equivalent) would be pretty ideal.  They'll flow up to about 220hp, the ballbearing design would decrease lag-time, because of the size you'd probably want an external waste-gate, no biggie.  These cars have been around long enough I figured there'd be tons of stuff like that.

Also, no real information on aftermarket camshafts.  I know Honda does a good job with things, but you can always improve.  Atleast increase the lift on both and the duration on exhaust... just a thought.

Also, not finding much about bumping the CR on one of these bad-boys.  The factory 7.5-7.6:1 is pretty conservative, is there any reason not to deck the head and bring the CR up to somewhere over 8:1 (adjustable camgears probably an issue)?  Just looking for a little insight.

Looking to drop a T2 into a 1G in a couple months, I caught the obvious mods section (exhaust, intake, IC, etc).  Just looking for a little more in-depth theory.  Perhaps I've been searching wrong, but I haven't really been finding much, any direction or info would be great.

[MUnity]

With a turbo car you don't need to increase CR just boost. I guess increasing CR would get more power off boost, but who drives off boost anyway?

[BOOSTBOY]

Im going for an increase in compression actually.  The new head im putting on has been decked in order to produce an 8.6:1 compression ratio.  This should make the bigger turbo spool up nicely and i wont have to run heaps of boost to get good power.  The Honda bottom end should easily be capable of taking the stress, especially as i wont need 30psi to make a decent number.  As long as it doesn't detonate it should be fine.

Oh yeah bino, im running a GT17BB and it seems the perfect match for the engine...

Cheers

Glenn

[Smithy]

Im guessing the GT 17BB
is a little bigger/floweyer/better than a GT BB15/15BB
right??
you need custom manifold for them???
guess dump pipe mods to for the external wastegate?!?

........

[Bino]

Boostboy, that's exactly what I'm thinking.  Anybody can get big power at 6K with huge boost, but I prefer an engine that's got some low end to it, granted it's not the same kind of power as a turbo, but it's better than stock.  I don't much care for turbos that come on like a light-switch, granted they're fun, but actually slower in the long run since you have to wait for the turbo to spool.

I had contemplated the GTBB17, is it the VNT design that I believe is found on the Saab's?  The 17 makes a lot of sense since it's a stock turbo for something, therefore can be found used and then rebuilt after some period of time.  

Those running the GTBB17, at what RPM does it really start to spool?  Thanks.

[QikLude]

Kelford Cams in christchurch NZ will probably be able to do a CAM regrind for ya..
something not to wild to upset the factory computer.

[BOOSTBOY]

The GT17 is indeed bigger than the 15 and is found on the SAABs.  On the city turbo engine you need a custom manifold.  It makes full boost at about 3-3500 but it comes up to this point nice and progressive, starting to spool alot lower than that.

[tur8ociv]

Hi All,

what sort of boost are you running. 3-3500rpm seems a little low to achieve full boost. Does it still accelerate hard after it has hit full boost or does the power start to flatten out.

Just curious, I'm seriously thinking of doing something the same.

Mick.

**We are all born Mad, but some of us stay that way**

[fordsorholdens]

For the turbo im going to put on my car i was thinking about puttin a needle valve on it  i know how to make it but ive heard the city turbo motors are knowen for blowing heads and gaskets when the factory psi is 12 i can boost it to 17-22 psi but im wondering what i can do to not blow the gaskets besides trickin the wastegate ???