How To Build A 7Age?

[Hans]

Hi Everyone,

 

I am planning on building a 7AGE 20V, i have an idea on how to go about doing this however i have some concerns and questions that maybe some of our experienced members here can clarify for me?

 

I currently have a 7AFE at home. and i plan on getting a 4AGE 20V front cut with all running gear and swap the bottom end with the 7A.

 

now the 4AGE 20V loves high RPMS, while the 7A block and its internals might struggle with that.

 

although i am aware that a swapping the bottom end the engine will still work, how well it will run is another topic..

 

so what i am thinking is

 

with the 7A bottom end - i'm thinking stock crank, forged rods and forged pistons.

 

then do the bottom end swap with the 4AGE 20V head.

 

the aim here is to have strong internals to cope with the demanding 20V head? forged internals will also allow the future prospect of turbo..

 

therefore my question is with this 7A and forged internals swapped 20V head..

 

am i correct to assume that this swap of the stronger bottom end can run with the factory ecu of the 20V reliably?

 

 

advice on this is greatly appreciated.

[Willis]

Are you going blacktop or silvertop 20v?

 

Your stock pistons will do just fine. If you're really worried about it, just give it a reco.

 

Aftermarket rods are advisable, some people do without them but I wouldn't leave it to chance if you want to rev the motor hard.

[Trev]

I say this everytime someone is building a 7age.

 

7a's don't rev high because they can't, they don't rev high because where the torque is produced there is no point revving them high.

 

The old race car 7age (7a, smallport head) was happy revving to 8800rpm.

[iwontarolla]

This is a good read and will most likely answer all your questions you have.

http://www.ae86drivingclub.com.au/forums/showthread.php/23444-Building-a-7age

[Hiro Protagonist]

I say this everytime someone is building a 7age.

 

7a's don't rev high because they can't, they don't rev high because where the torque is produced there is no point revving them high.

 

Agreed - peak torque @2800rpm is very handy for exiting corners a gear higher than a 4AGE.

 

If/when I finally build my 7AGE 20V I'd be looking at keeping redline around the 7k mark

[Hans]

_{Hey guys, thank you so much, i am very grateful for the input! whether it is a silvertop or blacktop will depend on what available when i go get myself a frontcut..}

 

_{so the 7A pistons are ok for this even for turbo applications?}

 

_{while i am defintely thinking forged rods. can i use the 20V pistons in the 7A with forged rods?}

 

_{i would assume that 20V pistons are better than 7A pistons? i could be wrong here..}

 

_{I say this everytime someone is building a 7age.}

 

_{7a's don't rev high because they can't, they don't rev high because where the torque is produced there is no point revving them high.}

 

_{The old race car 7age (7a, smallport head) was happy revving to 8800rpm.}

 

_{sorry should have clarified, i understand this. i was thinking of a redline between 6,500-7,200}

_{my idea of high revvin is something like 8000rpm upwards..}

[altezzaclub]

For the difference between 7000 and 9000 rpm you'd be quicker with a close-ratio gearbox, especially a sequential one! How well you get it all balanced will detemine how happy it is at peak revs too.

 

If you're going to turbo it in the future, how are you going to reduce the compression over the forged pistons? Can that be done with a 4AGE head? Spacers under the head gasket?

[ke70dave]

Don't be scared, run it high compression and on e85!

[flyinwall]

are you allowed to run lpg on the track cause if you run it on straight gas with the turbo it will be better cause it is a higher octane fuel (apparently)

Edited August 20, 2012 by flyinwall

[Willis]

Don't be scared, run it high compression and on e85!

 

Amen to that.

[Trev]

You have to really look at what you wanna build before you go doing it, there is no point in building a tough N/A engine now if you think you will put a turbo on it later on as the C/R will be wrong.

 

7a Block, crank and rods (upgrade to aftermarket if you will).

4age pistons and head

 

You can't go wrong.

[_FNQ_rolla_]

Like Trev said… Know what you want to build before you start to build.

 

Do a heap of research as different heads on the 7A block require different timing belts, if I remember correctly (don’t quote me) I think the Silver top on a 7A block needs a timing belt that has an extra tooth in the timing belt where as a Blacktop head on a 7A block will use a 4AGE timing belt. There is a lot of fabrication work needed to be done as that 15mm in block height will effect a lot of bolt on’s. If you are handy on a spanner and/or can fabricate this will help on saving the dollars.

 

Best advice to you is to know what you want and build your motor to what you intend it to be,

 

 

Now I have built mine with a healthy compression ratio and it’s turboed with big cams, forged internals, fully balanced and lots of head work and controlled with an aftermarket ECU.

 

I’m not after a dyno queen (big horse power) … I want something responsive and quick

 

All the best in your build

[Hans]

yep, i wont be building straight away...

 

this will be my daily..

 

but the compression is another thing I'm always thinking about..if i want to turbo in the future..i thought maybe i could get some custom rods made by ARP at the right length to play with the ratio..but it comes down to $$$ and fabrication $$$

 

for i'll stick to stage 1 for now :)

 

if i can get a reliable 7AGE 20V with forged internals running, might even scrap the idea of turbo..

 

this will afterall be a daily driven car with the added grunt :P

 

as for ECU, will the Stock 20V ECU handle it, i was hoping to do the build 7A bottom end and swap over

 

the car should strat and run as normal, but i can't help be get the feeling that a tune will be needed in rder for it to run "as it should be"

 

i don't know much about the ECU whether it can be reflashed or not, unless i have to fo full aftermarket ecu..

[ke70dave]

If its not a stock engine you can't run a stock ecu.

 

Anything more than a better exhaust and the stock ecu goes in the bin!

[altezzaclub]

You'd need a programmable ECU I'm sure, feel like building a Megasquirt?

 

How about quad bike carbs?