7AGZE Ideas

[Duk]

Alrighty, I'm bored and unmotivated, so I thought I'd chuck an idea up here to stimulate some more talk.

I'm in the throws of putting together some form of 7AG engine for my AW11. Now obviously a well sized turbo would be a good start for anything like this. But I always loved the pure low RPM throttle response of my 4AGZE and when I augmented it with a turbo (twincharged), it was better again.
So for something a little different, I've been toying with the idea of having an SC14 fed 7AG engine, with a small port head (maybe with bigger valves and, spruced up ports and combustion chambers), another version of my reverse collector inlet manifold, but with blow thru throttle body rather than the draw thru TB of the GZE engines. Again, my Pulsar GTiR intercooler, Adaptronic e420c, custom made extractors, 2.5" exhaust and maybe some water injection.

While the SC12/14 superchargers are hardly amazing in this day and age, I wonder about how much grunt I can get from 1 when the typical GZE type 'pre supercharger' flow restrictions are eliminated. That is, what can actually be had from them, when the SC is driven upto and maybe slightly thru its peek efficiency (no stupid boost pressure expected from it), with completely free flowing inlet to the supercharger.

And while I'm asking, can anybody tell me the distance from the top of a 4A block to the bottom? I want to know how much taller the 7A block is.

Thoughts????

[Hiro]

And while I'm asking, can anybody tell me the distance from the top of a 4A block to the bottom? I want to know how much taller the 7A block is.

7A deck is 15.4mm higher than 4A

[Hen]

It sounds like a good plan for low end torque fun.

I did something similar: stock smallport 4AGZE with NA inlet manifold, throttle post-SC, SC14 running 16psi. Just a bunch of parts I had and slapped together. Made 140rwkw when last tuned (with a torque peak around 3500rpm), but there would probably be more in it with some attention to the ignition timing on the dyno.

Really good fun but makes silly noises when getting on and off the throttle, so not so great for daily duties.

[trdee]

Nick parker is building an SC14'd 9A if i remember correctly. He may have some more insights for you once it is up and running (if it isnt already?)

[Duk]

It sounds like a good plan for low end torque fun.

I did something similar: stock smallport 4AGZE with NA inlet manifold, throttle post-SC, SC14 running 16psi. Just a bunch of parts I had and slapped together. Made 140rwkw when last tuned (with a torque peak around 3500rpm), but there would probably be more in it with some attention to the ignition timing on the dyno.

Really good fun but makes silly noises when getting on and off the throttle, so not so great for daily duties.

Yeah, the noise is 1 thing that puts me off a bit. I would go back to the conventional AW11 air filter layout, but with bigger plumbing, in the hope that it helped keep the racket down.

Did you still have the clutch on the SC and a blow off valve, Hen?

[Duk]

trdee, just out of curiosity, what head do you plan to use for your 9A build?

[trdee]

I have a blacktop 20v head for mine. Just need to collect a few bits and bobs for it to make it complete.

To be honest though - unless you're chasing the ultimate in performance, I would stick with a 16v head. Much cheaper and much easier to get parts for and just less of a fuck around getting the whole set up working nicely.

[Hen]

Yep, mine still has the SC clutch (switched using manifold pressure) and a biggish blow-off valve before the throttle. Despite being a plumb back BOV I never got around to connecting it to the inlet, so it's louder than it needs to be. Teenagers would probably love the noises, I'm just a bit too old.

[trdee]

plus you get to tell everyone you have a blow off valve on your gze

[Duk]

Yep, mine still has the SC clutch (switched using manifold pressure) and a biggish blow-off valve before the throttle. Despite being a plumb back BOV I never got around to connecting it to the inlet, so it's louder than it needs to be. Teenagers would probably love the noises, I'm just a bit too old.

With the Adaptronic, I controlled the clutch with a combination of MAP and TPS, so maybe a slightly more involved switching method could be used to help keep some of the funny noises at bay, along with a recirculating BOV and the AW11's long inlet plumbing (made bigger and better flowing).

[knightrous]

Ditch the SC14, it's a waste of time.
Go a twinscrew.

[Hen]

^^ A valid point, twinscrews are better. But at 10% of the price of a twinscrew and easier mounting/plumbing the SC1*s have their place.

[knightrous]

An SC14 has it's work cutout for a 4AGZE at moderate boost levels, stepping it up to a 7/9AGE is just going to put it further into struggles-ville.
If a proper twinscrew is out of the budget, at least consider a better roots blower like an Eaton M62/M90 which can be had for $500 or less and are completely rebuildable.
The M90 from a Thunderbird is a really nice package for conversions.


You can even get a shorter snout for them that would probably make it around the same size as an SC14.

[Duk]

While I hear your points about the SC14, and am in near enough total agreeance with you, the reality is that the M62 is pretty rare unless you get 1 new (and they're probably redundant, now) and the M90 wouldn't be working within its efficiency range (spun too slow), because it's too big for the engines capacity (and so it's overall flow rate) and can't really operate at a high enough pressure ratio (boost pressure).
So while the SC14 is a dinosaur, my idea is to get a decent amount of engine flow, via head design, attention to detail and maybe cams, while keeping the old donkey SC14 working within it's peak pressure ratio and speed range.

[nick.parker]

Nick parker is building an SC14'd 9A if i remember correctly. He may have some more insights for you once it is up and running (if it isnt already?)

Yep....I am....its in progress..should be up and running by the end of the year. I am going to be running the 1880cc (90mm stroke, 81.5mm bore) bottom end with a ported small-port head with FA sized valves and some custom high lift cams & springs. Compression is relatively lowish around 8.7:1 so that I can run 20psi on 98 octane later on.

Initially I was going to put the SC14 on there just to get started, but now I've had a change of heart. The idea was that in running the SC14, I was still going to spin it as fast as I am on my 4A setup, but the boost would drop from 18psi to 1587/1880x(18+14.7)-14.7 = 13psi. I was keen to see it the power was better than on the 4A due to much lower SC output pressure - however - SC speed is also a factor in the Rootes efficency....so long story shorter - I got an Autorotor 2087 about 8 years ago (a puny 870cc/rev but spins at 15Krpm continuous) which Ive decided to use instead.

Ron (Mr Twinscrew) and his bone stock smallport GZE made 260rwhp. So now the plan is to see what my setup makes on one bar with the twin screw, running lower boost than Ron, but more mods. Following this I'm looking at Sprintex's S5-355 http://www.sprintex.com.au/superchargers. Although quite large (1.46L - actually very similar to SC14's 1420cc) for the 9A setup, the idea of a 375kW ceiling is appealing - even if its just whack the small pulley on for a go at the drag strip.....and then back to the low setting for regular weekend duties!

Nick.