Building a throttle bodied unit - personal experiences

#1
Hello all,

As a mentioned in my introduction, I'm considering a Z22SE to move my oldie (Astra MK2) project.

I have not many premises in this build, but there are a couple of them. One, is to go NA, two is going throttle bodied. I know forced induction is "bang per buck" winner, but it isn't my goal, it's something for pure pleasure, and damn, lot of time since last time I was spending my time with a throttle bodied engine (it was a hybrid B20 VTEC Honda unit).

I don't need to go for top notch figures, the car is heavily modified handling-oriented, and I don't want to ruin it putting brutal figures. I want to be moving in the range of 200 bhp, and also, no need to build a top-end performer at 9000 rpm, I rather prefer to push torque a little bit more to the midrange, it's always more rewarding to drive in most scenarios.

Z22SE and all of those engines are vastly overlooked here in Spain, and I think they can be a good powerplant, all aluminium, modern, and probably very tuneable, but for some reason there aren't many of them squeezed here.

I would like to know about your personal experience/advice on this, since I can take different paths building it.

- How good are internals?
- Can they cope good with moderate power increase?
- Weak/limiting points?
- Do 2.2 work ok raising RPM's, or it worth to de-stroke them and/or use shorter 86 cranks?

I don't want to go for very big displacement (not really into 2.4 conversion, I prefer to keep 2.2 maximum), and they are hard to find here. Z22's and B207's & Z20NET's are more likely to be found.

If anyone can share it's personal experience, it will be appreciated.
 
#2
The z22se engine family loves mods, it was restricted at the factory for being too close to the z20let engine power

Weak points - always keep an eye on the oil level, the dipstick is useless at measuring the oil level;
be careful when tightening the spark plugs, over tightening them can cause the head to crack and leak coolant into the spark plug well, head is then scrap. Standard z22se pistons and rods are only good upto below 270 bhp

Bad point - not really bad but the z22se engine family uses a different bellhousing to any other engine, so you need a z22se / B207 /z22yh gearbox

Good points - a standard head gasket can take 500 bhp; crank and block is very strong

For over 200 bhp you need to use the standard z22yh pistons and rods, this raises the compression ratio to 11:1 and is good for upto 270 bhp

Add the balancer delete, open up the exhaust ports and fit some stage 2 cams and throttle bodies, this should easily produce over 200 at roughly 6800- 7200 rpm

Don't bother with the 2.0, the Opel Antara 2.4 engine is a torquey engine.

My own throttle bodied engine produces 270 bhp, but it's bored out and stroked to a 2.5 litre, revs like a bike engine because I also removed the mechanical water pump and chain.
 
Last edited:
#3
Thanks mate,

I found your post some time ago, and to be honest, it was the trigger to start considering the Z22SE.

I wasn't aware about bellhousing pattern, which is a hassle, as I wanted to keep the old F20, as there are many gearing combinations you can do and lot of stuff for those gearboxes.

I'll take a look to this subject, thanks for your advice!
 
#4
could be a good time to fit a F23 or go 6 speed, which would be cool in a mk2 astra.

The M32 is not as weak as people say, fill them with 3 litres of good oil and they are fine, but they don't like abuse. It's basically the same size as the F23 box.

I still regret getting rid of my champion GTE (aka London edition / leather edition)
 
#6
To be honest, the car will be intended to be road "legal". And I say "legal", because in Spain, doing the kind of mods I'm doing is almost impossible to get homologated/you are like a criminal. Anyway, I'll find out the way to do it, I've got a couple of ideas. 4-5 years ago I was looking to an event in UK, there was several options, Santa Pod, VBOA, and finally I attended to Goodwood FOS, I don't regret it, it was nuts, and honestly, I wouldn't mind to repeat. We were affected by flight controller strike and ended up driving, but the whole story was quite epic.

MK2 have something to me... they're special, just like MK1's, I've always wanted to own one. Maybe one day...

About gearboxes, F23 Getrag, if similar gearing as my ZLET, it's quite tall, and the gearbox itself a bit heavy. At this point, I think I would go for an M32. I can get a 6th gear, and being NA for road use or eventually trackday, I think it should be OK. Anyway, I can get this thing sorted later, lots of things to do.

If you are interested in take a quick look at my job, you can take a look at IG account (@el_batallas_400) meanwhile I start a thread about the car, it will take me some time to prepare pictures. I'll see if I can do it at night.
 

corsaZ22se

Senior Member
#7
Goodwood is a lot bigger show than VBOA which is just Vauxhall, Bedfords and Opels with the odd Holden. but you do get to see a wide range of cars from 100 years of vauxhall, standard cars, show cars, very heavy modified cars and everything in between.
the M32 box is lighter than the F23 but there are a few gearing sets available for both types only you may have to mix and match to get correct bell housing to suit the Z22 block. I did with the Corsa C and F23. ratio's from the 1.7CDTi Corsa with a z22 bell housing give 70mph @2,500 rpm (3.54:1 final drive ratio) z20let astra G is 3.64:1 final drive ratio. z22se astra G is 3.94:1 final drive ratio or Zafira A z22se is 4.17:1 ratio.
 
#8
I was playing a little bit with infos and ratios and gears and different variants...
1557321525810.png

Just to have summarized what's going on and compare with current gearbox... Also, was thinking about the possibility to get machined the front of an F18 bellhouse. First shot, it seems feasible, but it's something that needs to be measured carefully. I will take diagonal measurings of each pattern to compare.

F23 vs F18+ CR (one interesting option):
1557321750465.png

It might be near... Machining the hole and build a custom cap could be an option, plus the are way more compact and I have yet an F17 gear cable linkage that I would love to use.

One point mentioned, about cams. Anything to be said about valve springs? I've been digging into Cat cams web, and they don't state to be changed in any of them camshafts. In older C20XE's is well known if you are going to hit higher revs/lift cams, it's adviced to be replaced, but it seems not in Z22 case.

1557321994833.png

Something similar happens in rocker arms. Reliable enough?

Sorry for bothering with several questions, but I'm finding this engine really interesting, I think it worth a try.
 
#9
I did with the Corsa C and F23. ratio's from the 1.7CDTi Corsa with a z22 bell housing give 70mph @2,500 rpm (3.54:1 final drive ratio) z20let astra G is 3.64:1 final drive ratio. z22se astra G is 3.94:1 final drive ratio or Zafira A z22se is 4.17:1 ratio.
You have a good combo here! It's really interesting, I have som friends with combinations like this in F16's/F20's, but not in newer gearbox, that's cool!
 

corsaZ22se

Senior Member
#10
vocky is best one to advise on valve springs/throttle bodies. i would change the springs myself. Have Dbilas springs i 1 of the 2.2's and Schrick twin springs/cams in the other.
 
#12
I was looking yesterday to Dbilas site, and discovered they have plenty of material for Z22's, which was a good surprise. I had the car thread prepared on sunday and then laptop got stuck... I lost it, so I need to prepare again, let's see if I can manage tonight.
 
Top