7A-4Age Hybrid

[BANZAI!!!]

Hey guys, I came across this setup in a discussion at tafe and was wondering how effective this set up was and if any1 has done it here?

[Trev]

Hey guys, I came across this setup in a discussion at tafe and was wondering how effective this set up was and if any1 has done it here?

 

Have worked with them, the only way to benefit it is to use a bigport head as the smallport isn't enough but in saying that I know of a smallport 7age making 130hp and utilising the GE rev range (8800rpm), If I was to do it myself then I would go 7A block, crank, rods with 4age bigport pistons and head and that would be a starting point.

[BANZAI!!!]

Very interesting thanks for the feed bak

[Jono.C]

One thing with this is if you intend on do high revving etc the 7afe rods wont hold up to it much, the rods aren't as strong as 4age ones, so you'd have to factor in the price of forged/ stronger rods depending on what you want out of the engine

[machg]

a/ I made one just by bolting a 4age head straight onto a 7afe complete bottom end. Standard everything. Ran fine, drove like a 4age with a bit more bottom end pull. Exhaust has to be modified to clear sump for fwd applications, cambelt is Porsche 944 item for 4age 16V heads.

b/ Apparently the weakest part of the 7afe rods is the big end bolt attachment and this can be modified to accept stronger attachment (ARP stud and nuts?) Also standard Bigport 4ages start running out of puff before 7000 rpm, so unless you are planning to really flog it a lot, it MIGHT NOT be worth the expense of custom rods. (Just don't blame me if you build one and it craps itself, lol)

Edited May 2, 2011 by machg

[the_van_can]

Have worked with them, the only way to benefit it is to use a bigport head as the smallport isn't enough but in saying that I know of a smallport 7age making 130hp and utilising the GE rev range (8800rpm), If I was to do it myself then I would go 7A block, crank, rods with 4age bigport pistons and head and that would be a starting point.

 

my smallport has over 200xxx on it and it dyno'd 112.8hp on open headers with absolutely no mods but the ems computer. i would expect a smallport 7age to make at least 130hp, I guess a good ecu helps.

[Hiro Protagonist]

Most of the 7AGEs I've seen around don't tend to put out more power than a 4AGE with the same mods, but that's not the point of a 7AGE anyway - it is to merge the benefits of the low-down torque of the 7AFE with the top-end power of the 4AGE to create the best of both worlds. Peak power doesn't change much (and often lows the usable rev limit too), but the curve is much fatter down low where it counts, giving an overall performance boost (the good old "area under the curve")

[Trev]

Most of the 7AGEs I've seen around don't tend to put out more power than a 4AGE with the same mods, but that's not the point of a 7AGE anyway - it is to merge the benefits of the low-down torque of the 7AFE with the top-end power of the 4AGE to create the best of both worlds. Peak power doesn't change much (and often lows the usable rev limit too), but the curve is much fatter down low where it counts, giving an overall performance boost (the good old "area under the curve")

 

And this is where people go wrong, they think a stroker will = horsepower.

[LittleRedSpirit]

Area under the curve is where its at.

 

That's the whole point of everything I've done on my 20v since going in the new shell.

 

I reckon 20v 7age is pure porn. Need to do it seriously though, as you will want to be hitting high rpm.

 

You would need rods, pistons, fine tune your compression ratio. You would need a standalone ecu to let you get around the dizzy problem. Not sure which Timing Belt I haven't looked into it that far, but the 20v head flows more, especially if you aren't going to invest in cams and porting right away.

[machg]

Seem to remember a 7age 20V uses a standard 16V 4age timing belt, but I am getting old, LOL

[daCoupe]

A guy in my club just built one for his rally AE86 and had this to say:

 

"OK it runs!. got the 7ag built. did dyno runs last nite. Wow. picked up almost 20 more hp at 5500rpm. huge torque below 7000. peak hp is exactly the same as the built 4ag i had 3 yrs ago. 143hp at the wheels.( done at RCTS, his numbers are always low , but it compares to my previous engine) peak hp at 7200 where as the 4ag was at 7700. it will be nice to not have to thrash the hell out of the gear box and the engine to keep up. this is going to be fun!"

 

His build:

 

"sorry did not do a build thread, too busy . built so many engines, was just another one.

short summary;

mild porting done

stainless oversize valves.

same 304 cams,10mm lift as last year.

vitz buckets.

hks springs

10;1 pistons (.040) from redtop.

spool connecting rods from australia.

stock 4ac flywheel, lightened.

crank drilled for bigger bolts, used arp bolts from chev small block.

custom baffled and deeper oil pan.

new, red top oil pump.

cheapo ebay ex header.

same 47mm SK sidedrafts as last year(gutted) to use as ITB.

same SDS as last year."

 

As mentioned, it's not about sheer hp but rather usable hp/tq that makes the 7A shine.

[shayden]

ay mate what water and oil pump did u use and how did u run the water pump piping

thanks shayden :)