4AGE camshaft discussion... Your help is needed

[oldeskewltoy]

A few weeks back I posted my 4AG headwork ( http://www.toymods.net/forums/showthread.php?t=35553 )

Well, the bottom end of the engine is being built by Loyning's Engine Service - http://www.loynings.com/ They have built many winning F/A engines. Before you think out of the box..... this is NOT an F/A build... if it was, the polished chambers would have looked more like 30psi 4agte's head, then what I did, AND there would be a HUGE sucking sound near my wallet and bank account.

No, my aim in this build is to build a fresh 16V with aftermaket management that costs less than a used 20V BT conversion (here in the US of A) and makes similar, or better torque figures. I don't expect to make similar hp, for the simple reason I do not have any varible timing to get both the hp and the torque figures.

I do expect hp ratings, at the wheels, to be in the mid, to upper 130 range... and I'm shooting for a torque figure of 110 ft-#s, with 100ft-#s for at least a 3500 rpm span

Here are the specifications I gave Loynings....


1) Fully clean block, head remove all contaminants - check for cracks, for flatness, for need of line bore... all the regular machine shop work

2) Rod and main bearings are to be sized to standard clearences.

3) Rod deburring, a bit of lightening, and shot peened

4) the entire reciprocating/rotational assembly will be balanced to 8500 rpm. The balance will be the crank, rods, pistons. My aim is to balance the internals to "zero". I can then have each external item (pulley, flywheel, clutch) balanced to "zero" and the assumption is the entire assembly will remain balanced

5) block - .5mm overbore, fitting the 10 to 1 O/S pistons to specific bores. Fitting, and sealing plugs to the oil squirter holes. Machining head/block to get a final static CR of 10.75-11.00 to 1.
My plan is to have the block decked/head machined so that a stock headgasket (1.2mm) will have the same effect as using the TRD .5mm gasket on an undecked block/unmachined head. The reason for the stock headgasket is simple.... nothing seals better... longer.

6) flow checking the head...doing a TRD 3 angle valve job... putting the smallport head on the flow bench and check the flow dynamics(volume vs. velocity) and trying to maximize the powerband between 2500 and 8000 rpm.

7) head combustion chamber measures between 37, and 37.25 cc. If possible I'd like head machined to allow a 36cc-36.25 chamber. The amount removed from the head to achieve a 36cc chamber would be measured. This amount would be part of the total removed (head and block) to achive the static compression ratio in #5 above.


There is another required detail.... it MUST pass US emissions laws!!! That, and the rpm goals I have set for the bottom end pretty much restricts my choices to 272 type cams or less.... and I'm not all that sure I need a 272 cam for my goals anyway.....


So... what I'm looking for is the best cam combination to achieve my torque goals.... and I'm looking/listening for your suggestions, and reasoning.

[GTI-TRD]

I do remember reading somewhere (billzilla.org maybe) that using an exhaust cam a step (spec) lower or higher than intake cam can help shift your power band and torque curve to a more useable RPM range.
I would suggest 272 cams will be plenty enough duration, lift will be more critical to your torqure. A rally cam has good bottom-end torque and strong mid-range, revs to 7,500 RPM up to 10mm lift (underbucket shims) though so would suggest your emissions go out the window.

[oldcorollas]

well.. the compression will kill your NOx readings, the overlap will kill your HC readings...

either way, you will need to compromise, or fit 2 or 3 stage catalytic convertors to try adn reduce emissions...

fidn out the exact specs of the test, and adjust engine to suit.
if the test has limited low rpm range, then close your overlap for the test ... not sure what you can do about NOx tho (and i might be wrong on the correlations)

[abently]

My plan is to have the block decked/head machined so that a stock headgasket (1.2mm) will have the same effect as using the TRD .5mm gasket on an undecked block/unmachined head. The reason for the stock headgasket is simple.... nothing seals better... longer.

Are you sure you don't mean 0.8mm TRD Gasket as 0.5mm static Piston to Head clearance is too close on any Engine except motorbikes.....

Buy some Cam gears, adjust as necessary for Emissions testing and then back to dyno proven settings.

These aren't cheap > http://www.camshaftshop.com/camshaft...ge-16v-20v/36/

[oldeskewltoy]

Hmmmm, concerning the static CR...and gasket thickness.... TRD does make a .5mm gasket for the 4AG, so it has been done on a 4AG. More may need to come from the head... I'm pretty sure Loynings will tell me if they can't do it.


Cam gears are a given. Aftermarket engine management is also part of the package. It will be an FJO 341b Ver2 system w/individual coil packs There will be a few emissions targetted components. One will be sequential injection, the other, a wasted spark type ignition.

Some news... the cam I spoke of a few weeks back in a different thread (Colt's "Tri-Flow cams) does NOT appear to be available... That leaves Toda, HKS, Web, Tomei, Piper(Uk), Crower, and _____ who still make 264/268 duration cams.

Which of these will offer me the fattest, largest torque curve?????

[abently]

Torque and HP are related, so you want the one with the most Intake Valve lift assuming the ramp rates across all the various cams are the same...

Is it a shim under bucket design ? If not, consider changing to it as this allows higher ramp rates.

[oldeskewltoy]

Torque and HP are related, so you want the one with the most Intake Valve lift assuming the ramp rates across all the various cams are the same...

Is it a shim under bucket design ? If not, consider changing to it as this allows higher ramp rates.

Likely SZ one piece lifters

[abently]

Ok, found the 0.5mm Gasket does exist... If you can find out what RPM TRD ran their 4AGE built motors to, like this pic (but for the 4A-GE)



Then make a judgement on whether to go 0.7 or 0.5mm HG. Under dynamic conditions the piston weight, along with conrod strength + rpm will determine which gasket to use. I'ld go as far to say, using stock rods + not super-lightweight pistons will achieve a "squish amount" the same as using TRD Forged conrods, pistons and 0.5mm Head gasket under dynamic conditions. There is not much to gain by going tighter then 0.7mm unless your competing in a restricted rules class and have the time and effort to deck the block 0.2mm at a time till you see very light piston to head contact on a 100rpm over-rev.

I'ld strongly advise against it and personally have never gone tighter then that on proper all-out rebuilds. The gains after 0.7mm are not worth the expense.

Maybe find someone who has personally done a similar build with the 0.5mm gasket and removed the Head later down the track ? The TRD pistons may actually sit 0.1mm below the deck of the block etc.... all unknown quantities..

Sorry if I've given you more to think about.

[oldeskewltoy]

ASSUMPTIONS..........

a) With a 1.2mm gasket... everything really depends on the deck height - stock block with a stock piston how much of the deck can be removed???.

b) via BASIC calculations I calcultate the current CR to be 9.8 to 1.... - using a stock head gasket on an undecked block and unshaved head with the 10 to 1 pistons, and the increase of 3/4cc (2%) do to the CC polishing.

c) An 81mm bore USUALLY allows an accurate guesstimate of 1/10 of a mm = about 1/10 of a CR point when it comes to headgasket thickness and CR boost, so if I'm at 10 to 1, then I'm looking for about 7/10 of a mm....



I can take the head back down to 36cc, that will bring the CR up to 10 to 1. The gasket diff will get it up to 10.7...

I could have the head taken down a bit further... say to a combustion chamber of 35cc, this would allow a bit less decking....?????


As you said more to think about..........

[abently]

To get the Piston the Head clearance you want, you'll have to shave the block deck. No doubt about that. 0.5-0.7mm off the deck is minimal so all the holes will still line up correctly with the HG.

Decking the Head 2mm (if needed - assuming a deck thickness of 5.5mm) is fine so long as it does not reach any valve seat inserts. You may need to go thicker on the washers underneath the Head bolts, but that's all.

[oldeskewltoy]

no opinions on camshafts??? Cmon... this group has never been shy before..............

[abently]

Ok, I looked at all options and the TODA 264 10.3mm Inlet/Exhaust will be the best duration/valve lift wise.

The ramp rate on the TODAs' is even higher then the maximum possible ramp rate Kelford Cams designated for their 'maximum velocity' cams, so I'ld recommend getting the recommended TODA Valve train Kit ( http://todaracingusa.com/product?cid=23&id=250 ) to match it up correctly.

[af300e]

I agree with the 272 degree sentiment. Don't go too crazy, you may ruin the driveability and definately the emissions. 200hp 4age's that make good power at less than 7000rpm are generally not running 300deg cams. I have a book with many examples of cams/comp ratios/hp readings for 4age's that I can consult if you wish. If it were I, I'd lift the comp more, perhaps to 11.8 or even 12, retard the timing slightly to suit (prevent pinging) and go with 272 cams. The 4age head is pretty modern, has decent squish which allows you to run good comp ratio pistons and retard the timing whilst making excellent power. Earlier hemi heads with little or no squish seem to need the crazy advanced (eg 30btdc) to make power and this does restrict the comp you can run. Still, even on shit squish heads, 12.1 is possible on road fuel.
Emissions will be your issue with this.
Cheers
Andrew

[turbo4agte]

Im pretty sure you're not going to pass emissions if you put cams on a 4AGE with 10.7:1 compression. Either you wont pass emissions or you wont make your HP goal. I think you are asking too much with 100 ft/lbs by 3500 RPM. Your going to need LIFT to get that type of torque, and by the time you're fuelling it properly you will be over on NOx.

But good luck anyway. Im looking forward to your results.

[abently]

Yes ok, he will probably not pass emissions...... maybe think about water Injection or running a high % of methanol for the yearly test ?