Re: 2tgue & 3tgtue info
Originally Posted by chippa07
Reply With QuoteI just did a very quick search of the old forums and got this quote from "dcleyne". don't know whether he is still around but credit where credit is due. i didn't read it all but i reckon it will help.
btw, unfortunatly it doesnt tell you how to tell the difference visually between 2t and 2tg, it tells you a fair few of the differences.
2T-G head has different manifold stud pattern on inlet side. Inlet manifold is not compatible between 2T and 2T-G.
Water pump shaft on 2T-G is shorter and the pully has a different offset. Pumps, pulleys and fans are not interchangable with 2T.
2T and 2T-G both bolt up to T50 series gearbox with standard bellhousing.
2T-G twin carb manifold is standard DCOE pattern.
Later 2T-GEU has electronic distributer.
2T-G crank is forged?
2T and 2T-G mechanical fuel pumps are not the same. 2T-G pump actuator arm is longer. 2T item might be made to work on 2T-G.
2T-G requires dummy cam to drive distributer and fuel pump.
Early 2T-G uses same block as 2T. Late (2T-GEU) uses same block as the T18 13T.
The 2TG's with 1600 on the top are the very first of the Early 2TGs the cam covers varied with the later 2TGs and 2TGEUs
The First 2TG (11111-88220) Had "Toyota" and "1600" on the rocker cover.
The 11111-88222 Rocker cover did not have "1600" on it. It had its EGR valve mounted there so only had "Toyota" on the Left Hand Side.
The 88260 Head appears to have received two styles of Rocker cover. The 88222 Version and the one used for the 88261.
The 2TGEU 11111-88260 and 11111-88261 heads Had "Toyota DOHC" on them and the DOHC lettering had raised edges.
The 2TGEU 88262 Rocker Cover had "Toyota DOHC" on it and the DOHC was not with raised edges.
There are two types of 2TG head without any casting numbers. The first is the early 2TG head, The pre-production TRD race engines were not numbered.
The other type is the 11111-88262 head. It is not marked on the casting anywhere.
The number can however be found on the cam itself as the second half of the cams part number. ie xxxxx-88262
The 88220 series head had smaller valves than all of the other variants which had the same valve size.
Standard 2T-GEU injectors flow 220cc/min
Later 2T-G heads (>260) had double valve springs.
Some flow gain examples from porting and Polishing 2T-G heads
2tg 220 head on flow bench 420 thou lift 200 hp. After clean up and exhaust porting 210 hp
2tg 222 head on flow bench 420 thou lift 204 hp. After clean up and exhaust porting 214 hp
2tg 260 head on flow bench 420 thou lift 206 hp. After clean up and exhaust porting 216 hp
2T-G Cylinder Head Installation Tightening Torque 720 ~ 880 kg-cm (52.0 ~ 63.5 ft-lb)
Specs for the 88220 and 88222 Cams:
2T-G Engine modifications as per April 1973 were from Engine Number 2T-8038333
Firing Order: 1-3-4-2
Ignition Timing: 16 Degrees BTDC / 800 rpm
Compression ratio: 9.8:1
Bore and Stroke: 85.0 x 70.0
Valve Size: Intake ? 43mm (Up to April 1973)
? 44.5mm (April 1973 Onwards)
Exhaust ? 37mm (Up to April 1973)
? 38.5mm (April 1973 Onwards)
Cam Shaft: Lobe Height In 45.87 ~ 45.97 (Up to April 1973)
Lobe Height In 46.37 ~ 46.47 (April 1973 Onwards)
Lobe Height Ex 45.87 ~ 45.97 (Up to April 1973)
Lobe Height Ex 46.37 ~ 46.47 (April 1973 Onwards)
Cam Lift: In 9.82 (Up to April 1973)
In 10.27 (April 1973 Onwards)
2T-G/3T Hybrids
---------------
3T pistons must be used together with a 3T crank.
2T and 2T-G pistons must be used with a 2T crank.
3T-GT block will require modification to seal the oil return.
the 3TGTEU ECU DOES NOT control spark. It is a fuel only system, based on an early bosch design, similar to the 2TGEU EFI system. The spark is controlled only by the distributor, which has internal
weights & vacuum advance/retard, whereas an ECU controlled dizzy would have the advance mechanisms locked, like the early distributor 4AGE's. The 3TGTEU ECU doesnt know squat about
whether it has 4 or 8 spark plugs. each pair fire together anyway.
3T-GTE exhaust manifold is the same port and mounting as for 2T-G (and therefore 2T)
The 3TGTEU inlet manifold will not fit the 2TG head. the ports are completely different spacing & size.
The 3TGTEU head can be put on the 2TG block.
3T crank will not fit early 2T-G but works ok in late 2T-G (>260).
When using 3T crank in late block, the pistons will need to be fly cut to avoid valves.
I believe CA18DE 270cc injectors are bosch top feed style, and as such, will fit your 2TG manifold, dunno about the plugs though, but they can always be changed. The CA18DET injectors are
definately this design, but are closer to 400cc.
A set of 3TGTEU injectors would probably be ideal, at 295cc.
Generally, when going from standard 2TG pistons to generic 3T pistons and crank, the compression will be increased a bit, from about 8.8:1 standard, to about 10 or 10.5:1.
Using the 3T setup, the cheapest is to use regular 3T-C pistons with the exhuast relief cut a bit deeper. 86mm are available new.
2T-G pistons had different compression depending on the year and other things. Older ones were about 9.8:1, latter ones were 8.8:1, some were 8.4:1, some 8.3:1. A standard 3T will have a
compression of about 9 to one. Using this bottom end with a 2T-G head increases the compression because the 2TG head chamber is slightly smaller, 62 vs 68cc.
Wiseco sells 10.5:1 3T-C pistons off the shelf. They will clear the 2T-G valves just fine and with the 2T-G head they come out closer to 10.8:1 1941cc with 89mm bore.
18 R Pistons fit 2T Conrods and they take your bore out to 88.5mm However depending on type Compression may be awkward to calculate.
If you're using 2T-G head on your hybrid you should use a 2T-G block as supplimentary drive cam will suit your application. With creative fitment of cam bearings 3T-G block can be used.
The oil pumps interchange between 2T and 3T(GTEU). The 3TGTEU pump is a Higher volume unit!
All the T series engine use the same size Rods. They vary in strength but are all the same length (Excluding the 1400cc T engine)
The 3TGTEU and 2T, 2TGEU etc also all use the same basic block design. there are some minor differences but the deck height is the same on all of them. It is the Pin height in the piston itself that
counters the increased stroke of the 3T crank, Hence the need for 3T style pistons and the inability to use 2TGEU pistons with a 3T crank.
CAMS.
Firstly 2TG and 3TG cams will interchange ! So any cam grind you can get for a 2TG will fit in a 3T-GTE.
The reason there are more grinds for the 2TG is that not many people play with the cams in the 3T-GTE, Turbo performance is relativly new when compared to N/A performance !
Then you have to consider that in a N/A engine the cam does all the work as far as dictating how much air gets into the head. (Valve size and ports aside) With a Forced induction engine the Turbo
jams it in there so the cams are generally paid alot less attention.
A Turbo's cams also use a whole different set of rule as depending on your desired result Overlap is not such a good thing !
VALVES
Ok excluding the 11111-88220 head the 2TG's and 3T-GTE's have the same size valves ! The first version of 2TG head (88220) has smaller valves on both the inlet and exhaust.
2TG Valve Size: Intake - 43mm (Up to April 1973) (88220 Head)
- 44.5mm (April 1973 Onwards)
Exhaust - 37mm (Up to April 1973) (88220 Head)
- 38.5mm (April 1973 Onwards)
HEAD FLOWS
Ok Head flow is ONE of the more important characteristics of a head. But it isn't everything. You also need to consider the chamber design, Sqish area's, the actual flow direction and turbulence, the
placement of the spark plug or plugs, Airspeed and probably a dozen other things I have no idea about.
The second thing to remember is the cams will dictate just how much air gets in. Headflow figures are measured at certain lift points of the valve. If your cams only give you 300 tho lift then there is no
point worrying about what happens inside the head when you have 400 tho Lift as the cams don't get there !
I for example had my head rebuilt to suit the engine I am building. It was flowed and the cams were made to accomadate the figures we acheived. In turn the intake manifold and Throttlebody needs to
meet the same flow requirements or its all a waste of time.
2TG v's 3TGTE
To be honest I can't answer which one is best ! There is still so much I haven't had the time or money to test! The heads use a different port design and both work very well in their designed
applications. In stock form the cams and intake manifolds limit the engine operation long before the heads do.
If you take the cams and manifold out of the equation then in stock form you can make a base line comparison. I used a 88261 EFI 2TG head (As per my engine build) And yes it does perform better than
a 3T-GTE Head flow wise how much better varies at each lift point.
As for chamber design and squish areas etc. The 3T-GTE head is apparently a better design. I am not really able to offer an opinion on that as it is too far out of my ability and learning.
BUT
Before you all go ditching your 3T-GTE heads bring it all back into context ! You only need the head to flow as well as your cams and intake manifold can support! You also need to remember that an
intake manifold can not only restict but increase the airflow thru a bare head. A well designed intake manifold will channel in more air than a bare head will flow alone (Even on a flow bench when the
air is being channeled)
Then there is the ancient mystical voodoo art of head porting! I can only evaluate the performance of my Personal 2TG head. I am still trying to obtain a well ported 3T-GTE head for comparison. Given
the 3T-GTE's better chamber design then it would be desireable for a ported 3T-GTE head to outflow a Ported 2TG head. I honestly have no idea if it will but I have never seen Toyota, TRD or TTE use a
Turbo 2TG head !
Also a mild port job on a 3T-GTE will generally cost less than fitting a 2TG head.
More resources
http://ourworld.compuserve.com/homepages/stepho/en g2t.htm
..and while we're at it
http://ourworld.compuserve.com/homepages/stepho/ce lfaq.txt
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