TIII Tech Questions..
The T-III and T-IV both used the same FORGED crank. Although, the balance shafts were different.
The balance shafts were custom tailored to the application. The T-III required a different balance due to the change in resonant frequency. In other words, the T-III generated vibrations, at different RPM ranges, than the T-IV did. This required the shafts to be uniquely balanced to properly cancel those vibrations (resonant frequencies), within the proper RPM regions.
Applying that information... Yes the 2.5 shafts were also unique.
T3 pistons- forged or not?
Someone writes in: T3 pistons are not forged. I have it on the authority of a few people, one of them Ed Peters and being he was involved in the development of the T3, I believe him. I think the myth was born due to misprint in some of Chrysler books and due to the fact that T3 can run higher EGT's then T1/T2 which is due to better combustion chamber design.
Indeed the T-III pistons are/were forged.
A quick check... Cast pistons react differently to heat. They will expand and contract more than a forged piston will; Thus the expansion strut. Turn a T-I, T-II, T-IV, or a 2.5 piston over. The expansion struts are the impregnated metal re-inforcements at the top (from the under side) of the piston. This helps maintain piston shape before, during, and after temperature transients.
Inspect a T-III piston for this same part. It will not be found. The forged piston does not require the use of this component. This is why forged pistons are run at a tighter clearance spec, than cast. Under full load (high temp's) the forged piston's expansion/deflection is minimal, when compared to a cast piston.
Additionally: All of the T-III blocks were machined at the Saltillo plant, in Mexico. Why? They were able to keep the tight spec requirements for the forged piston application, along with other reasons. Close inspection of the cylinder machine code, (i.e. the 'A','B','C', or 'D' stamped on the under side of the block) on the T-III engines will indicate consistent machine sizes. If my memory serves me correctly nearly all of them should be "C's". In any case, they were kept very consistent (Nearly all will be the same letter). Inspection a Trenton block (i.e. most T-I, T-II, and T-IV's) may expose a cluster of cylinder combinations. For example, 'A'-'C'-'D'-'B' or 'D'-'D'-'A'-'C'. Their spec.'s were not maintained as tightly, as the Saltillo plant.
EGT's: EGT's aren't so much dependent on combustion chamber design or shape, as they are on hardware capability. The pistons, exhaust manifold, turbine housing, exhaust valves, etc.. have more to say about capable EGT's, than combustion chamber shape. The shape of the combustion chamber has a greater effect on knock sensitivity, emissions, burn-rate, pressure rise, etc.. In any case, high EGT's can be achieved with ANY combination, as long as the component quality is there.
If the part in question is the T-III component, it helps redirect the coolant across the front of the block. The T-III coolant exits on the driver's side, of the head. The "path of least resistance" (coolant in the block) would be to enter the block, go to the rear of #1, turn right, travel across the back of cylinders 2, 3, and 4, and exit out the thermostat housing. This produced "coolant stagnation" and hot spots at the front of the block. The direction plate is split in the middle by a plate, with a flared tip on the back edge. This flared tip would influence coolant to make a sharp right turn, upon entry to the block. The simple part was just enough to eliminate nearly all of the stagnation and restore adequate/proper coolant flow.
Concerns: Placing this component on a 8-valve engine can cause too much of the coolant flow towards the front of the block.
With the 8-valve head, the "water-box" is in the front of the head. The normal coolant path (in the block) would be to enter the block, go to the rear of #1, turn right, travel across the back of cylinders 2, 3, and 4, turn right (towards the front of the engine), come back across the front of 4 and 3, and exit. Obviously, the coolant is being transferred into the head, throughout it's path; But a large percentage of coolant will be taking the stated routes. Too much coolant may desire to make the sharp turn and exit the block, from the front. This can generate the same T-III issue, but at the rear of the block.
If the
part is desired: If this part is desired on an 8-valve application, then
the flair/baffle size could be reduced. A rough estimation may be to reduce
the flair/baffle to approx. 10-20% of it's total size.
Please
remember to shim the bottom water pump mounting location the same thickness
of the "re-director"/coolant baffle. Using this part/these mod's, on an
8-valve head, are at your own risk.
Benefits...
unknown.
On installing a 84-88 water pump on a TIII...
Ed wrote: Hold on. If you go with an old style water pump on a T3, won't the blades be rotating in the wrong direction? That will lead to totally inadequate pumping and thus cooling. Reduction of cooling something that you do NOT want to do on a T3, it is marginal to start with...
This is true! We do not want to change the pump rotation. There are many different length accessory belts available, that will work great as a replacement. Therefore, obtaining a longer belt and rotating the pulley in the correct direction - The pump will rotate properly. It should also be mentioned, that there are pulleys available (proper tooth count) that , with slight modifications, will adapt right in. The Lotus is a high RPM breather and will appreciate the extra high RPM cooling.
On cylinder head cracking...
WOW!!! 3 cracked heads in 69,000 miles??!! I'm still on my original head at 110,000 miles with the steel plugs!
The original freeze plugs were inserted at 80ft. lbs of torque. This is a "BIT" excessive for a freeze plug. Add this to the thin wall that surrounds the tapped hole and ... Using the original plugs can be safe if they are simply removed, cleaned, and re-installed only to a "non-leaking" torque, while using a light sealant.
How much power do you think it's (exhaust manifold) good for before you think it's a major restriction?
The major cork in the T-III system, amongst other things, was the turbo. Bolting a GOOD breathing assembly (on the stock manifold) could yield up to 400+HP, with the proper calibration. The +40's will be full-on to accomplish this, seeing that the RPM requirement will be so high. I went 'round and round', with Gus, on this one. If you base the HP capability, of an injector, on 100% of its flow... Then yes. BUT there is a "cooling" requirement placed on the fuel which is NOT necessarily used/spent fuel. This lowers the available HP capability of ANY injector, because a good percentage is used for EGT control and NOT HP.
Any other problems do you think I will run to at elevated HP levels? This will be a pure race vehicle so i'm not concerned with long term Lotus head problems (cams, cracking, timing belts, etc...)
Have ARP make up a set of head
studs. The stock bolts... well.. The head should have the freeze
plugs removed. Lotus installed them to 80ft lbs. (A bit excessive for a
freeze plug/bolt). This was the TRUE reason they cracked, not because they
were steel. Aluminum ones still exist out there. If you cannot find them,
reinstall the steel ones only tighten them enough to keep them from leaking.
The combination of belt wrap (or lack of) and high seat pressure (127+
lbs.) was responsible for the cam belt failures. The spring rates are good
for
approx. 9000 RPM. This was
also a bit excessive for an engine that had a 6600 FSO point.
What effect on the motor if a TII gasket is used? The MP TII gasket looks more robust then the OEM TIII gasket and I was just wondering.
Per another post on coolant "re-directors".. Those changed holes help manipulate the coolant transfer location and rate. Since the T-III water box is on the drivers side (as opposed to on the front) of the head the coolants desired direction had to be modified. This is the reason for the hole changes. I am not saying that the T-II will not work. I am concerned about hot spots.