7MGTE, Truck Motor Torque Build (7MGTE + GT3071R discussion)

[kaiser]

Ok I started this thread on *another forum* and wanted to see if SM's Finest had any input.

Ok, So I am currently building a 7MGTE that I would like to use in a 4x4 truck for off road fun.

So instead of going for big numbers High RPM I will be shooting for low end torque.

I know the 7M is perfect for this (without going UZ) becuase of its under square bore to stroke ratio.

So Far I have:
8.9:1 JE pistons (Not 100% on the CR, I will check when I get home)
Mildly PNP Head
Stock valves
Chevy Big Block valve springs
1.4 Titan Motorsports MHG
ARP everything
New oil pump
Adjustable cam gears

Will be ordering MAPECU2

I was looking at BC stage 2 cam shafts, is this a wise choice to optimize low end torque?

Would I be better off going with a twin turbo setup with the OBX TT manifold?
Or would a single get me what I need?

GOAL: 240+ ft/lb before 3000rpm



Is there anything else I can do to squeeze more torque out of this motor?

There were many useful responses

Best bet for maximum torque is to make everything geared towards making low RPM power. To that end, stock cams will probably be the best, especially with those adjustable cam gears. The OBX TT manifold is set up for Greddy 3 bolt inlet flanges just like the original Greddy piece, and sourcing turbos to fit that at all, let alone turbos that would suit your power goals, is basically a 'not gonna happen' sort of thing.

What you'll want is a small single turbo like an internally gated GT3071R or something similar. Have a fabricator make you an adapter to go from a CT26 flange on the stock cast manifold to a T25 or T3 flange directly. Running an internal gate means that boost will come on more gradually, which will make it easier for you to modulate the throttle in 4wd climby situations.
You might even consider something even smaller like a GT2860RS. The sooner you're making full boost, the sooner you're into your big torque curve. If you're dead set on full boost before 3k I'd go for the GT2860RS, as while that turbo will be maxed out around 325whp, it's responsive as hell on 1.6-2.0L 4 cylinders, which means it'd be even more responsive on a 3.0L. It'll fall off and die in higher RPM compared to more traditional options seen on 7M-GTE's such as T61's, etc. But it'll be very strong below 5k and that's where you'll be making torque.
In short, you will have to go to a smaller frame turbo on a T25 or T3 footprint from a cast manifold to best achieve what you want. CT based turbos will NOT get you there, and T4 based turbos aren't likely to either, even if equipped with a QSV.
Because you'll be running them on a 3.0L, consider the larger hotside available for whatever turbo you choose, as larger engines need the reduced restriction and being a 3.0L it'll spool those little bitty turbos like crazy even on their 'big' turbine housings.

So I have done a little research and using the GT3071R as my Turbo and aiming for 350 HP which would be approx. 35lb/min, the compressor map tells me my Pressure Ratio should be around 2.8.

So if I bring this over to the Turbine map, I get a little confused but I think the .64AR is my best bet.

Right?

Yes, a cast manifold will almost always beat a tubular manifold to boost threshold. Where tubular manifolds shine is in higher RPM stuff and overall backpressure reduction.

The turbine flow map is how much gas can flow through the turbine at a given pressure ratio. Your backpressure will always be higher than your intake pressure, and so running the .64 will bottleneck your overall power band and elevate EGT's and generally limit how much power you can make in a big way. Remember we're not talking about a .64 turbine housing on a P-trim T66 here, it's a little GT3071.
The .86 will spool a little slower, yes, but you'll get a lot more out of that GT3071R as a result, and most of the gains in response will be seen from running such a small turbo on a 3.0L to begin with, particular on a cast manifold.
That said, I don't have any data or any experience or results from anyone that's run a GT3071R on a 7M-GTE. You should also consider the GT3076 and GT3082, although those would both require an external wastegate.

So about the cam shafts, My stock cams were out of spec (journals measured too low) Is it worth tracking down some GE cams or just replace GTE cams?

My standing questions are:
Cam Choice?
Will running such a small turbo at rpms above 4000 be bad for it? Will I have to bring my redline down?

Any other input would be greatly valued!

 

[Crypton2006]

I would stick to stock cams. The only problem i can think of might be over spooling, you might want to run a very large external WG as opposed to a internal waste gate. You have to get alot of exhaust gas away from the turbine if you want to be able to control that thing. But as a disclaimer i am talking out of my butt, as i have never tried to run a small turbo. I ran a Garret T4 60 trim and had a boost threshold around 2800-3000. 22psi by 3500-3700 made 500whp. I don't think you need to go as small as your thinking.

 

[planemos]

What are you using this "4x4" for? Good god... must be rockcrawling... Just do a double transfer case and change the diff gearing.

 

[kaiser]

Crawling and Mudding and hauling around toys like dirt bikes and jet skis.
Good call on the large external WG.

 

[Crypton2006]

Here is my dyno sheet...240 ft lbs at around 3600. This is a low compression motor about 7.5:1 stock cams stock intake manifold.
Turbo i was running on this graph is a Garret journal bearing 60 trim T4. .68 undivided turbine housing on a stock exhaust manifold. Im running a 4.33 rear end and torque is not something to be lacking with this setup.... I think you can get what you want without limiting yourself of the top end especially with your 9:0 CR, throw in some adjustable cam gears and there you have it...240 ft lbs by 3000 and 400-450 whp. And i was only running a map ecu 1 v1 at the time. No timing control.

 

[Nick M]

Use the GE intake cam. Don't enlarge the intake ports, you will lose low speed filling ability.

 

[Enraged]

stock turbo can do it easy. check my build thread for mod list:

 

[Crypton2006]

That looks like a auto trans. Correct?

 

[Enraged]

mine? Nope, 5 speed. that was also before the new clutch, so it might hold more now.

 

[kaiser]

More Great Info! Maybe I can do this stock manifold and an upgraded CT-26

 

[kaiser]

Now the fun part is finding GE intake cam and a GTE exhaust cam in good condition because my journals were way out of spec.

 

[Jesse Heiss]

Any progress? I gave up looking for good cams as they all have nasty journal scoring. Went ahead with BC 264's and my machinist was able to touch up the journals in the head. SIP racing carries stock cams if you're dead set on those. You're in the exact same pickle I had my head in trying to decide on a turbo for low end. I'm really curious to see how your's turns out.

 

[Backlash2032]

The exhaust cams are exactly the same. I have a GE intake cam I would be willing to let go of.

 

[kaiser]

Update!
Motor is in truck and turns over HOWEVER Broken wire in harness between CPS and ECU Gave no spark. Probably for the best as I forgot a freeze plug behind the front Timing Cover (Machine shop gave me a bag of plugs and didnt include that freeze plug. My dumb ass fault for not checking)
More on that here
http://www.supramania.com/forums/sh...nt-in-oil.-No-BHG.-HELP&p=1900623#post1900623



Any Way I re did the entire harness with new shielded CPS cable and Coax Knock cable with braided sleeving to make it pretty. Will try to post pictures later. I have ordered the plug and the gaskets needed to remove the front timing cover to replace the plug. Will do it in the spring when I am done the rotation I am on.

Done:
-JE Pistons
- New Bearings
-ARP Everything
-1.3 MHG
-All new seals & Gaskets
-Walbro 255
-AEM FPR
- AN Fuel lines -8 sending -6 return
- Shimmed new oil pump and new oil squirters
-PnP Head
- Comp Cams Valve Springs
- new valve guides
-3 angle valve job
- Marlin Crawler Re-enforced R154/R150F Hybrid Tranny
-Locked front and rear with Chromoly Axle Shafts
-Lex AFM
-Modified EBAY Divorced Down Pipe

In Progress
- RC550's comming soon
- Full 3" Catless Exhaust (need to weld)
- Mount aluminum Rad
- 1JZ Coil Mod

Empty bay

Dual oil filters, I am running a cooler

Something's missing in here

Interior in, painted black, all controls work, blower works

Power seats from a MK III Supra, yea they work

Hydraulic e-brake hooked up

New lines

How she sits

R series tranny mated to the 7M

Freshly rebuilt Toyota 7M-GTE

Stock turbo

Don't know what to say to this

No comment

In tha baaaaay

Dropping it in

You have to drop it in with the trans bolted up due to lack of clearance by the firewall

And shes in

Whoo!

 

[kaiser]

So I bought the truck from a friend who was rocking a built 22RE but wanted to swap in a 1JZ. He solid axle swapped it, bought a cab and box rust free from South Carolina and then ran out of money.

So I bought it from him and brought it to my friends garage. (not my flag)

Here is how it looked the first day I got it

So I began rust proofing the truck and installing the gas tank (PO had hacked off the stock mounting brackets)

I bought new fuel lines, break lines and Energy Suspension GM transmission mounts for engine mounts.

I had to make custom engine brackets

 

[IndigoMKII]

Ew, Fram filters..

PnP will remove some of that low end torque you were after.

 

[kaiser]

I did not enlarge port size, simply removed casting lines and flaws as well as smoothing the lip from the pressed in valve seat.

Plus I did all this before I decided to put in in a Truck,

 

[Zrain25]

A Diesel engine would of been sick. But a 7mgte will be sick too

 

[Another MkIII]

One thing to take into consideration would be cooling. The 7M is not forgiving when overheated. I've never been offroading, so I don't know for sure, but I would think mud and dirt plugging the radiator could be an issue. Build looks sweet though, good luck!
-AM3

 

[kaiser]

One thing to take into consideration would be cooling. The 7M is not forgiving when overheated. I've never been offroading, so I don't know for sure, but I would think mud and dirt plugging the radiator could be an issue. Build looks sweet though, good luck!
-AM3

This was also a worry of mine, for the mean time I will be using a single 10" push type fan with a larger all aluminum 89 Celica Turbo Radiator, 10"X5"X1" Setrab oil cooler and possibly a fuel cooler in the future (I have all the parts for a fuel cooler I am just unsure if I want to do it.

You are certainly correct about off roading. Cooling is a big issue because of the slow speeds. There is a lack of cool air flowing through the car. Like rush hour except the engine is constantly under high load.

I also have ambient temperature to my advantage. In Timmins (where I will live with this truck once it is done) The July (hottest month) average high is 24.2°C (75.6°F) with a year round daily mean temperature of only 1.3°C (34.3°F). We do not get blistering hot summers.

For inter cooling I will just be running a straight pipe from turbo to the 3000 pipe but down the road I will be replacing the 3000 pipe with a water to air inter cooler.

Keep the feed back coming boys! I am finding it handy!