engine build

[rich_86]

looking to build a strong NA 4age engine over xmas wat kind of combos have people got the make decent power out of them no forced induction... cheers rich

[rthy]

i am slowly building up my engine heres my current combination of parts that it looks like i will be using:

4age 20v: block, crank, oil pump, quad throttle bodies


4age 16v: pistons, possibly 4agze, possibly spring retainers, one vernia cam gear

7afe: cylender head

timing belt: I have no idea yet

custom/off the shelf aftermarket bits:

- trd 16v valve springs
- custom made intake manifold
- spool rods

I may look into the fitment of the exhuast valves out of either of these two engines

thats all I can think of right now


but this definetly an engine built I would sujest for anyone unless they are prepared to do some serious work

[rich_86]

cheers where u located

[rthy]

S.E suberbs of vic

[johnny_08]

why the 7a head?, dont pple use the 7a bottom?

[tricky_dan]

Sam_Q what sort of money are u looking at spending? im in a similar situation-will get me an 86 or 70/71 in the uni hols (4 months :D ) and start building it a bit~

[Javal]

why the 7a head?, dont pple use the 7a bottom?[/b]
Correct, however Sam is doing something a little different.

Although the Stock 'F' heads flow alot worse than the 'G' heads, with some working over there is alot more potential in the 'F' head once some money / alot of work has been put into it. i'll let sam cover that one in more detail.

The reason this is not common practice is that not too many people want to throw huge amounts of cash into headwork (at this level atleast) when they could just use a mildly cleaned up 'G' head.

[Gilly]

and Sam is a "pioneer"

basically he makes this shit cool, if successful the 7A head will be another mod for peeps to look into

all because someone bit the bullet and did it

[rthy]

johnny: yes people use the 7a bottom end for a cheap (all relative) way to increase their capacity from stroke alone. I personally did not go down this road, this is because of personal preferance of liking to rev the ring out of my engine, hey I like it ok!! hehehe

Javal said it well, looking at the diamter of the ports I am sure they flow really crap and I am going to have to do some very serious work to make it flow well and make good power but I think I have worked it all out how. However it has three main things that make it have more theoretical potential over a G head:

- first the biggest is that the angle of the inlet ports are pretty much like a motorbike and edging closer to a F1 head (will post a pic soon),

- shallower valve angle, although everyone says wide = power times are changing, over time engineers found that even though a narrower valve angle should in theory flow less and lets there be less max room for valves it overcomes it with less surface area in the combustion chamber, better combustion chamber shape for distance and how it burns and the list goes on. In my own research I have found that over time engineers started with wide valve angles and huge valves (18rg) but kept closing them up over time, proof of this? a F1 engine has a narrow valve angle!

- better combustion chamber shape: it has a shallow recessed valve layout, this allows for an unsual mod to the head that makes the combustion chamber into a more ideal shape. I unfortunetly cant talk about this, I would like to but I have promises to keep.

Dan: Comicly enough I am looking not that much more money than my original 20v buildup, its kinda hard to work out but I think less than 2K without cams? But thats because I am going to do everything myself. I am at this stage going to use some pretty normal pistons though so I am saving big there, from what I have worked out my ideal piston choice from what I have is mahle (ACL) forged "low comp" pistons that I would then modify to suit the block and head for a more ideal combustion chamber shape. I dont sujest this to anyone who hasnt done some massive research and has some good workshop facilities. I am no genius but I but think I have somewhat of an ability to read books and absorb heaps of it. I have 5 books from america coming right now and one from a friend as we speak that I will need to read before I can go much further. I have to confirm some theries before I can continue.

Gilly: thanks but I am no pioneer, Bill Sherwood is (nice guy too!). He gave me the idea and I did my own research into it from there. When I first seriously thought about using a F head it happen to correspond to some increadable info I found from a book that I coincidently ordered around the same time, ironicly enough I ordered it to confirm a theory I had on collector design in the exhaust! He however in his build is using custom parts and is chosing what very much seems like the ultimate, and good on him too. I am however doing it with mostly off the shelf bits that are modified and a fair bit of custom fab work and on a tight budget too.

But I hate to admit it with my current heath it might take me years. I mean for 2 weeks now I was meant to do a simple job on my head and I could not. Things might change soon though.

[lo_rolla]

Mines still in the planning stage cos I'm a poor cunt.
But so far I've planned:
11+:1 Forgies, Billet rods, Silvertop Block, Balanced and nitrided silvertop crank, 16V head, 304*8.5mm cams, shimless buckets, springs, oversize valves, 10+ angle valve job (CNC Newen Valve seat cutter, fuck yeah!), quads and every thing else.

Good thing is it's also my job, a Gasket set you pay 700 for I pay 250 for.

So hopefully it will work out at around 7 to 10K in parts and tuning and I do all the machining and fitting. Will let you know how it goes....in about 2 years! aha.

[rthy]

sounds good, I managed to get my silvertop gasket set ordered for pretty cheap too from a guy on toymods.

Any ideas on which model pistons yet?

[johnny_08]

sounds good and complicated :P but would all the mucking arround be worth the effort? guess we'll have to see hey, u are the man sam

[rthy]

hey i am only the man if it works! if it doesnt i am just some random loon! as for the mucking around being worth it, i have no idea but shit it will be fun! the way i see it it wont cost that much to build the head by itself and if things really dont work out i am going back to my 20v blacktop top head.

also i have to say i am seriously getting cold feet about this, as i have been getting more and more commited in this build i have thoughts like "what if it blows up?? or makes no power", i just need to keep going and find out.


also i just finshed whipping this up:

http://www.ae86drivingclub.com.au/dcimages/4/8/4/3/156219.jpg

[beerhead]

Sam, Timing belt is an easy fix, I bet the 4AFE will do it. You'll probably need the lower timing cog off one too. If you're really lucky 4AGE valves will be a bit taller than the 4AFE ones and you'll be able to regrind the cam rather than looking for a billet item.

[rthy]

Sam, Timing belt is an easy fix, I bet the 4AFE will do it. You'll probably need the lower timing cog off one too. If you're really lucky 4AGE valves will be a bit taller than the 4AFE ones and you'll be able to regrind the cam rather than looking for a billet item.[/b]

if I was using the lower cog off the 4afe engine then it would be ok. However I plan to use the 20v lower cog because I have a vernia cam gear for a 4age 16v for the top. Fits nice but it means I will need a shorter belt. I am thinking maybe a 4ac one?


hey rich: what engine building knowledge and recources do you have?

[rich_86]

was think 4agze block, not sure on head yet but will be ported and polish and cc'd. custom tuned length manifold, blanced crank and rods, forged pistions compress ratio say high 10s to 1.. still looking at camshafts...looking for around a 9 -9.5 k redline... prob run dual injectors per port std 4age one on custom rail. usually other pics like oil cooler, 2 core radiator, uprated alot of things mainly for reliability. yea basic run down...got 2 86s the other has got a 1jz going in and will become the daily jus a bit of fun cheers

[rthy]

if your going to be revving it that high then you will need an agressive cam in it to have a need to rev it up to there. I think this will lower your dynamic compression ratio so you probably will need over 11:1 compression to compensate. Valve springs will also need to be changed as will your rods.

[rich_86]

wat degree cams u reccommend sam Q???? and do u no the piston size for the big port 4age??? cheers rich

[rthy]

well if you want to have power around 9000rpm then probably 295 to 205 degrees, but I am no expert on the suject. It will be a total bitch to drive though. If you want an all round engine then maybe something around 260 to 270 degrees?

also around 9.5mm lift on the intake and 8.5 on the exhuast should in theory work nicely

[terryo]

cams with advertised durations above about 277 degrees are very difficult to drive smoothly on the street. they give a very lumpy idle unless you have quad throttles, which "tames" them a bit. certainly as you hit 280+ duration, you will have negligible low down torque and need extensive tuning with a good programmable computer and inlet/exhaust to match. there is not much point in using such long duration cams unless you have extractors with the correct pipe length--do some research on this!!.
any 4AG cams with lift about about 9.5mm and duration above about 270 degrees, will be prone to tossing the top shims out of the cam buckets. of course this is not a problem if you have a 20V head or a shimless/shim-under conversion. some heads will need metal removed to clear the lobes on 9.5mm of greater cams. its down to the individual casting. the 20V head does not need such agressive cams to perform properly.
I've done very sucessful 7AFE & 4AFE modified engines/heads, so that part of this thread is a good idea. the 2 biggest hassles are suitable cams and getting suitable inlet manifolds to clear under some bonnets. we made a custom quad set up that is now on a AE92 producting over 200hp at flywheel
I'm happy to help with parts/machining at good prices if you want to assemble it all. none of this is difficult if you are patient and do proper research. lots of pics on www.roadandtrack.net.au. Terry

[rthy]

well said terry, great info as usual

oh also do you have pictures of that quad throttle inlet? I want to see if its simular to my design.