4AGE rally engine specs - thinking out of the square

[rallysprinter]

The engine in my AE86 rally car has done a lot of work, so over a period of time I've been collecting parts to build a replacement engine.

I want a strong engine that will run between 4000-8000rpm all day in competition on 98 octane. I’m not chasing sheep stations, so I’m not going to buy really expensive brand new parts, when I can make do with a cheaper alternative. Most of my disposable cash goes on running and maintaining the rally car, so I don't have a lot to spare to buy expensive parts all in one go.

I've been collecting parts to build a Bigport/smallport hybrid 4AGE with great midrange performance. But Bermy's thread "Long rod 4A or how to destroke a 7A" got me wondering if there is other option outside of the square. http://www.toymods.org.au/forums/showthread.php?t=80558

As far as rules go, I have 2 option to choose from: Club rally Cars, or Production Rally Cars and here's an extract of both:

Club Rally Cars
3.1 ENGINE SUBSTITUTIONS ARE PERMITTED SUBJECT TO THE FOLLOWING CRITERIA:
(i) the engine shall be from the same manufacturer as the car;
(ii) the engine shall be of the same type as the original; eg, a car originally fitted with a piston engine shall remain
fitted with a piston engine;
(iii) the engine shall have the same number of cylinders (or rotors, if applicable) as the original car;
(iv) turbo/superchargers are permitted only where fitted on the original car.

or

Pre 1986 Normallly aspirated 2WD Production Rally Cars
Must use "The original mechanical parts necessary for the propulsion"
• The bore and stroke and therefore the capacity is free within the limits of the homologated
or recognised engine block. The crankshaft is free. The car shall be classified by its resultant
capacity

Obviously, putting in a different engine in is going to cost more in fabrication, and will probably need a rebuild anyway.

So far I have accumulated:
Both small port and big port heads
7 rib oil squirter blocks and a 7 rib non-oil squirter block
1 x early crank (40mm big ends)
2 x later cranks (both have thrown a bearing)
sets of bigport and smallport rods
set of spool rods
set of hastings chrome rings
set of standard bore 4age hypatec small port pistons
set of TRD shim under bucket cam followers
set of adjustable cam wheels
set of SuperTech single valve springs
200m Toda light weight flywheel
Haltech PS 500 ECU
EFI Hardware 45mm DCOE quad throttle bodies
EFI Hardware Air box
Redline Bigport DCOE manifold


I'm thinking about using this cam, which has big lift but moderate duration.
Catcam 7105148 - 268/260 with 10.7/10.25mm lift.
www.catcams.co.uk/acatalog/7105148.pdf

So, am I correct in going with a big lift 4AGE, or should I be thinking about something different?

Thoughts?

[MRMOPARMAN]

i have been looking into this for a while, as i have an aw11 id like to turn into a rally car one say.

with PRC, im fairly sure AE86's only ever came out with 3 rib blocks and big port heads, correct? so thats what you will be required to run. iirc though the mains are the same size between 3 rib and 7 rib, so in theory you could put blacktop internals into the 3 rib block.

if it were me though, i would buy something like a '5A' stroker kit from places like MRP. a peaky motor wouldnt be ideal for rallying. look for the broadest torque curve you can get.

if you go CRC, i think the cheapest way would be to go a 3sge beams package. although a peaky motor itself, you will find they will have an abundance of power right through the usable rev range in a light car such as an AE86.

does CRC have a championship yet, or they just tacked onto the PRC guys with no placings or anything?

[little blue fury]

my 2 cents stay with the plan of the high lift 4age, as good and nice as these motors are with quads, hows your t50 box? albains gear in it? have you changed the input shaft?
the old man has rallied these cars and motors for years now, when we changed the box, HOLY SHIT..... the motor just pulled and pulled. engine rpm was always above 5500 -8800

[rallysprinter]

Thanks for the opinions Guys,

with PRC, im fairly sure AE86's only ever came out with 3 rib blocks and big port heads, correct? so thats what you will be required to run......

I've been talking about this to a couple of people. Current thinking is that any 16v 4AGE is ok in an AE86. Running a variable valve timing SR heads on SR20 engines in Nissan Sunny, that never came out with those head was a similar example that was given to me.

does CRC have a championship yet, or they just tacked onto the PRC guys with no placings or anything?

Down here CRC does have a class but it has all type of CRC cars in , ie no engine capacity classes for CRC

.. hows your t50 box? albains gear in it? have you changed the input shaft?

A W55 box for me. On the large/heavy side, but takes abuse. A close ratio box would be great but the $ figure scares me off.

[webby]

For PRC I would use a high comp (~11.5:1) 7 rib with smallport head with some 288 cams. good for the 4000-8000 range.
for CRC I would go 7afe block with MRP 83mm Crank with Spool Import 135mm rods and some OEM style piston (may need a slight shave of the piston) again with the above head and cams.
Should be good for 170-180hp easy. the later with some nice torque fro corner exit!!

just my opinion though

[MRMOPARMAN]

Thanks for the opinions Guys, I've been talking about this to a couple of people. Current thinking is that any 16v 4AGE is ok in an AE86. Running a variable valve timing SR heads on SR20 engines in Nissan Sunny, that never came out with those head was a similar example that was given to me

its all well and good saying "these guys get away with stuff, so why cant i" and just go do it, but you will be spewing if they come along and tell you you cant, then you have to reblock your car.

if you look in the manual of motorsport, they make official engine allowances all the time. perhaps you should write to them and ask for the allowance, since changing from 3 rib to 7 rib would give no performance benefit anyways.

[bermy]

Alright, disregard the first comment, just got a hold on the rule book.

In what class of PRC are you looking to race in? Cut away between Class P2 and P3 is 1.6L... if you increase displacement to 1.8L with the 5A stoke kit, you'll be racing against 2L cars. Might be a bit better off racing in the P2 and limiting displacement to 1.6L no? Now if you can change engine block from a 3rib to a 7rib, maybe you can get a 3rib 7A block in there and drop the displacement down to 1.6L

[rallysprinter]

Alright, disregard the first comment, just got a hold on the rule book.

In what class of PRC are you looking to race in? Cut away between Class P2 and P3 is 1.6L... if you increase displacement to 1.8L with the 5A stoke kit, you'll be racing against 2L cars. Might be a bit better off racing in the P2 and limiting displacement to 1.6L no?

If not using a 4A block, then it is a Crc engine, and there are no capacity classes for CRC.

PRC P2 means 4A block with no oversize at all. That's what I'm in at the moment.

Thsnks for the comments though.

[oldeskewltoy]

any rules pertaining to the head.... or mods to it?

[rallysprinter]

any rules pertaining to the head.... or mods to it?

Modification of the original cylinder head is free, save that the original number of valves and camshaft(s) shall be retained.

Material can be removed but not added so ports can't be moved.

I'm going to have to mark room for the high lift cams for starters.

[oldeskewltoy]

depending on the quality of the casting... the "magic" number for needing to clearance the cams is 10mm cam lift (give or take) Good port work is worth its weight in gold! Local shop near me (Atlantic builder) is cranking out over 260hp on 77mm stroke(stock 4A stroke). If you are seriously considering adding stroke, you should look into O/S valves. Not that O/S valves don't work on standard stroke... they do... but O/S valves in a stroked A is almost required.

Ted's (Kamikaze Kams) has a high lift, short duration cam you might consider - KK108. They also have a KK108E if you want a tad more lift

[rallysprinter]

Ted's (Kamikaze Kams) has a high lift, short duration cam you might consider - KK108. They also have a KK108E if you want a tad more lift

Thanks, the Kaimkaze Kams, Cat Cams and Kelford cams all come out to similar costs.

Thanks to everyone's input. I think that I'll continue to stay in the P2 class with a standard bore/stroke 4AGE and run with the big lift cams, porting and as much compression as I can get out of smallport pistons and 0.5mm head gasket etc.

[bermy]

I guess if rules state that you can remove as much material from the head as possible, I'd check piston to valve clearance and shave the head as much as you can get away with your cams. Stock pistons are already below deck so you'd retain the stock squish band around the combustion chamber and only remove combustion chamber volume by thinning the head. Stock smallport pistons + 0.5mm head gasket will only get you to around 11:1 ish, good for stock cam timing with under 270° cams, but if you really want to go to town with that engine, you'll definitely need more.

[BrianGT]

Great posts from everyone and I would just add that deciding on what class you want to stay in is the real clincher, it's from there that you can decide on mods.

A friend over here runs an AE86 but our rules state that because it's a twincam, even though it's only 1600cc it has to run in the 2 litre class against BDA's which it just can't compete. He had throttle bodies etc and it put him in to that class.

He's now had a Group A engine built, at vast cost, with plenum chamber and it puts out 198bhp but because it's now "std" it competes in the 1600cc class.
A little off topic I know but deciding on your class is the best way to go.

[rallysprinter]

CAMS, the governing body has just released a bulletin, today, in relation to the regs for PRC, that I currently compete under, that allows the substitution of a 20v 4AGE for any car that had a 16v 4AGE.

http://docs.cams.com.au/Regulations/...PRC%202014.pdf

So, this is now a further option, and attractive in that I could remain in class P2, under 1600cc and probably have better performance than yhe big lift 16v.

Any estimates in the cost of getting a blacktop 20v into an Ae86, assuming it doesn't need a rebuild? I would keep the haltech ecu and loom and sell off my 16v parts I've accumulated.