2TG-3T Hybrid Discussion

[Celica_73]

SeptemberSquall

Thanks for the advice I'll look further into it then Goodman just said due to the cam overlap that the pressures while filter and cause more problems thens it's worth.



Born-Enthusiast

Ok fuel I'm running is BP ultimate (98). The engine place didn't recommend running anything high then 10.5:1 for street use with this engine. Due to fuel limits etc. Lack of fuel doesn't seem to be a problem. I'm just running stock fuel pump, fuel pressure was check and told to be fine. Turned out the timing a had running on my engine was actually spot on, Goodmans changed and played around and ended bad where I had it so ignition wasn't my problem is was just simply the CR. When the engine was on the chassis dyno (second engine rebuilt) the operator had also of problems trying to get the fuel ratio correct and the engine still died! I'm not sure if you have sorted out your problem yet or not but if your still having trouble consider dropping the CR down to 10:1.
Just out of interest what did you engine power curve look like?

[SeptemberSquall]

SeptemberSquall
due to the cam overlap that the pressures while filter and cause more problems thens it's worth.

wtf does this mean please clarify

[Born-Enthusiast]

I haven't actually seen a graph of the engine power curve yet as the final tune hasn't been done. I have to fix my fuel issues before we can time the engine correctly and then open it up all i can say is it produced over 100hp at 5000RPM before it leaned out significantly and we had to stop or risk blowing the engine. Oh something you might find confusing is we have both had pistons fail (I believe i used the same brand as you too pistons and rings), yet on the rebuilds we took different approaches. You lowered your CR and I made mine go higher. When I rebuilt we made the valve relief smaller then the previous attempt. Meaning I had the machinist actually shave off less when flycutting the pistons. I also had to shave the head due to part of piston 1 being pressed into it.

Now I have ran my engine for nearly 5000KM not going over 5000RPM due to my fuel issue. My old build only lasted 1000KM and blew at 4000RPM. have you changed anything else in your engine? Like maybe valve springs or cams?

The only other thing I can think of and it has been previously stated is that both our valve reliefs where cut too deep. your comparison between your new pistons and old show your new to have shallower reliefs. Can your problem not have been your CR but the loss of integrity in your actual pistons themselves from the fly cutting. You said you only blew one piston didn't you each time where I blew 2 at once, just a thought. sorry for the long winded reply

[Celica_73]

Sorry SeptemberSquall that was ment to say the pressure/vacuum due to the cam overlap would flicker/fluctuate to much for the vacuum advance to work correctly.

Born-Enthusiast
The head has been the same in all build and was only touched on the last build to help reduce the CR. As for the Fly cut the new cut is actully deeper then old as the new piston was cut from and older piston. Cuts may appear shallower due to piston dome machined down a little. Piston used in my build were endurotec psitons I believe yours were from ACL so not cure if they are the same or not. Also I believe that cast piston don't like high CR either. Are your figures at Wheels or flywheel.

[SeptemberSquall]

Sorry SeptemberSquall that was ment to say the pressure/vacuum due to the cam overlap would flicker/fluctuate to much for the vacuum advance to work correctly.

at idle i can understand that, at cruise conditions i would have thought you'd have a stable enough vacuum state to establish a steady vacuum advance.

[oldcorollas]

at cruise you should still have vacuum, but it will nto help at idle..
still leave it on as when you are doing 3k or 3.5K (or 4k??) ont he highway, there will be vacuum, and any advance will help.
you can soften the vac advance spring to allow it to develop more advance with less vacuum... and as soon as you put foot down the vac advance goes away..
no point in not running it, and a chance it will be beneficial... so.. why not

[SeptemberSquall]

at cruise you should still have vacuum, but it will nto help at idle..
still leave it on as when you are doing 3k or 3.5K (or 4k??) ont he highway, there will be vacuum, and any advance will help.
you can soften the vac advance spring to allow it to develop more advance with less vacuum... and as soon as you put foot down the vac advance goes away..
no point in not running it, and a chance it will be beneficial... so.. why not

x2

mind you i took my car down to the tuner to get tuned the other day and somehow got a car back untuned with 1300 dollar bill, and for some reason they rebuilt and recurved the distributor with less advance and vacuum advance removed?

ffs i was happy with 40 deg total all in at 3800 now i got to set it at 20deg btdc static to get that before i was getting 40deg total from 15deg btdc static fucken and y remove my vac advance without asking? or even with asking? asked this question, answer: 'when you have big cams and high compression you remove it..." yeah, i say, but why?

response: "_________________"

/rant

42313131440

[Born-Enthusiast]

x2

'when you have big cams and high compression you remove it..." yeah, i say, but why?

response: "_________________"

/rant

42313131440

Isn't it obvious? to make the list of things the workshops done a little longer and therefore are able to charge you more!

[Born-Enthusiast]

well your not wrong mate cast pistons definately are not as good as a forged set. They can take a bit though or I should have blown my engine again. I only got my engine tuned in the car so the readout was from the wheels. I should be fixing my fuel issue this week. If i can get it back on the dyno I'll let you know how it goes.

[Born-Enthusiast]

Ok Good news Engine is running and producing pretty good power.

So quick update
Cams used are Camtech Profile 401A
Current CR is 10:1.

Piston from last destroyed engine pictures included as you might be able to see the valves were just touching the piston. There are also photo of the the new piston machining used in current build beside the old cracked piston.

Current results from the engine on the dyno
Max power was 151bhp @ 6500
Max torque was 140ftlb @ 5000

rpm bhp tor
2500 52.1 109.4
3000 66.4 116.2
3500 82.2 123.8
4000 101.5 133.5
4500 119.1 139.4
5000 133.4 140.2
5500 139.6 133.4
6000 149.7 131.6
6500 150.9 121.9

Those interested final carby jets were MA 170 M 135 P 60

Cheers again for all those who gave advise
Jason

Are these your final power outputs? that is quite impressive. or have you continued to fiddle and work it abit more? oh also in this build from what i can understand you changed the cams correct, are they aftermarkets (bit of a stupid question to ask). Lastly are these considered mild or hot cams for the engine?

[af300e]

'when you have big cams and high compression......

What is your static comp?

310 deg cams or similar? Is that your build?

Have you dyno'd yet?

[jeffro ra28]

Just for the record, Endurotec pistons are different to ACL duralite.

From my experiences Endurotec pistons are of better make. Not by much.

Endurotec are sourced primarily from "precision international"



Celica 73. You have had this engine built 3 times correct?. It was built the first 2 times with ACL duralite? I noticed the difference in your comparison photo's.

I think the reason why your engine has lasted this time around is because you are using a different piston. Which may have been proved by you to be a better qaulity piston!?

[SeptemberSquall]

What is your static comp?

310 deg cams or similar? Is that your build?

Have you dyno'd yet?

10.3:1 310/288 adv 260/248 @.050" .411"/.395" lift at valve with .015 clearance

[Celica_73]

First of all SeptemberSquall & oldcorollas replies about vacuum advance that was my thought hence why I was asking the question. I'll go get myself a MAP sensor from the wrecks and have a play cheers.

Born-Enthusiast
Yes those are the figure I receive from the tuner with the engine in it's current state remember these readings are at the flywheel not the wheels. Cams have been stated a few time through this thread already they were reground to a Camtech profile 401a.

Grind No...Advertised Duration....Duration.................Cam Lift
......................@ ×010²..............@×050²
.................IN.........EX.............IN..... ........EX.........IN........EX
401A.........293°......293°..........242°......... .242°......372².....372²

From my understanding these are classed as mid cams or Rally cams. The profile idea I received from TheToyman75 after purchasing his head.

jeffro ra28
All 3 build are meant to have Endurotech pistons. Last rebuilt has a combination of piston from first and second engine that weren't damaged and the rings from the second engine.


Advance curve as it currently stands is Static is 12 degrees Starts to advance at 1280rpm till 3000 where it's 32 degrees then to 7500 max at 34 degrees.

[Born-Enthusiast]

cheers for that. A little off subject, but does anyone know what the specs are on the cams used in the 2TG's 11111-88222 head? I would like to know how different these are to your own.