1HD-T Intake Manifold Modifications (3 Viewers)

[ForealBoreal]

I have heard a little by a few people trying to get some high end performance out of the 1hd-t and even 1hz engine. Now the traditional thing of throw a better turbo, an intercooler and play with the pump a little can get you so far and even very far it that.

I have heard that a big bottleneck in the whole system is the air intake manifold. I have seen at least by my reading people who tend to cook 1hz's for an example usually have cracking in cylinder 1 and 6. This I think has partly to due with having less air being fed into those cylinders due to manifold design. I think a lack of injector maintenance also has to play with this as well. I am a believer if your turbo can handle it the more cold clean air getting into your engine the better.

I have also heard John or Phil at Ateb have done some modifications to an intake manifold to allow for better air flow. I am wondering if any of the lower mainland BC guys know any info on this.

Commence discussion

 

[TheBigBoy]

It's mostly depending on the turbo size as far as performance goes. With a large turbo the intake mod can give 20-25hp alone. The heat and cracking of the HZ is more idi than air restriction as the DT engines share the same intake. Either way its a definite plus, having stored air right there ready to be pushed through the engine at will.

 

[sailor]

The 81 the Ateb boys did the custom scratch built intake manifold on was in response to the owners desire to have a blisteringly fast rig. It is truly that quick, both off the line and on the highway. My 81 is quite a bit stronger than stock but this one leaves me for dead. Apparently wheelspin is a major factor on dry pavement as it is also part time. All that torque exposed further issues in the drive train, notably the need to do a lot of work to the transmission (A442F Hydro).

When this truck takes off on boost it sounds like some prehistoric beast is very pissed off...

Ateb also re- pistoned the HDT and did their full tuning mods as well.

Interestingly, John's Prado has a custom huge intake manifold as well and that thing is seriously fast. He also beats the crap out of it off road and it holds up so he has obviously got the famous Prado issues under controll as well..

 

[ForealBoreal]

It's mostly depending on the turbo size as far as performance goes. With a large turbo the intake mod can give 20-25hp alone. The heat and cracking of the HZ is more idi than air restriction as the DT engines share the same intake. Either way its a definite plus, having stored air right there ready to be pushed through the engine at will.

I think cracking of the 1hz is a combination of a bunch of reasons, lets not get into this can of worms here in this thread.

Take Graeme's Gturbos, his Badboy or Headkicker turbos would have some serious induction being pumped into the engine. Guys running 20-30lbs of sustained boost. Its gotta help this out.

 

[TheBigBoy]

Yep, it will definitely help running high boost. Just remember all the little things add up. I have a new turbo from Graeme (unknown to me at first - sneaky Graeme, very sneaky ). Only 1 made so far. I only plan on running 25psi max. so the intake mod your talking about, I've just done. With all the other mods adding up. This thing is going to be a torque monster. So I can't say how much this mod alone makes. Only complete figures after I've tuned it, and dyno'd it.

 

[ForealBoreal]

The 81 the Ateb boys did the custom scratch built intake manifold on was in response to the owners desire to have a blisteringly fast rig. It is truly that quick, both off the line and on the highway. My 81 is quite a bit stronger than stock but this one leaves me for dead. Apparently wheelspin is a major factor on dry pavement as it is also part time. All that torque exposed further issues in the drive train, notably the need to do a lot of work to the transmission (A442F Hydro).

When this truck takes off on boost it sounds like some prehistoric beast is very ****ed off...

Ateb also re- pistoned the HDT and did their full tuning mods as well.

Interestingly, John's Prado has a custom huge intake manifold as well and that thing is seriously fast. He also beats the **** out of it off road and it holds up so he has obviously got the famous Prado issues under controll as well..

the guy is on the forum right? wrongwayaround?

 

[Dougal]

When this truck takes off on boost it sounds like some prehistoric beast is very pissed off...

Awesome.

 

[mudgudgeon]

Search around a few turbo petrol/gasser performance forums. The riced up gassers use large plenum intake manifolds that taper off toward the last intake runner. Good ones have cones/trumpets ay the intake runner to smooth air flow into the intake runners.
The size of the plenum is roughly equal to full engine capacity or more. Ie, 4.2litre engine would use a plenum with a volume of 4.2litres.
The theory is there is adequate intake charge are stored in the plenum all the time so no cylinder is starved of air.

A 1HD-T would benefit from better intake runner transition from the plenum, port matching of intake runners to the head, porting of the head, port matching exhaust ports to manifold etc. None of it in standard trim has been optimized for maximum performance

 

[TheBigBoy]

Search around a few turbo petrol/gasser performance forums. The riced up gassers use large plenum intake manifolds that taper off toward the last intake runner. Good ones have cones/trumpets ay the intake runner to smooth air flow into the intake runners.
The size of the plenum is roughly equal to full engine capacity or more. Ie, 4.2litre engine would use a plenum with a volume of 4.2litres.
The theory is there is adequate intake charge are stored in the plenum all the time so no cylinder is starved of air.

A 1HD-T would benefit from better intake runner transition from the plenum, port matching of intake runners to the head, porting of the head, port matching exhaust ports to manifold etc. None of it in standard trim has been optimized for maximum performance

Did you do all this already? Intake and porting etc. if so, what was the results?

 

[sailor]

Yeah, The charge air enters at the front where the plenum is largest and then tapers rearward. Ports are matched.

 

[TheBigBoy]

Oh, I hate that type of intake (enters at front). They even sell them on ebay over here.
http://item.mobileweb.ebay.com.au/viewitem?itemId=130781417087

 

[Tapage]

Oh, I hate that type of intake (enters at front). They even sell them on ebay over here.
http://item.mobileweb.ebay.com.au/viewitem?itemId=130781417087

that's sweet .!!!!!!

 

[TheBigBoy]

There's much better designed ones out there. And the key is to get the volume/cfm right. Anymore creates lag. Any less reduces air. Hopefully mine is just right.

 

[ForealBoreal]

Pictures????

 

[sailor]

Hey that is cool on EBAY.. I agree that too much volume creates a ton of lag, just try a Safari intercooled HDT with a stock CT26... The intake made here is tapered and doesn't have the extension on the rear end... The truck has minimal lag and a ton of power...

 

[wrongway around]

graeme has a new turbo design to match the enlarged ported intake,interesting. tricky controlling surge ,with a tappered plenium. designing an intake is like designing a turbo. if that intake is 'proven', on ebay ,sounds pretty good ,you should buy it . i myself am pulling my custom turbo out (running 28 psi)and putting in a cheap chinese knock off (and hope i can boost it up enough to maintain my egts). my hp thinking is that atebs pump tune and fuel mods along with the tweeked manifold is all these trannies can handle extreme t/c ,v/b or not . oh i might add that atebs screaming prado that sailor is talking about is running the cheap chinese turbo too.

 

[TheBigBoy]

Really? A cheap Chinese turbo? What model turbo? Ct26.

What model of Graeme's turbo are you talking about?

 

[wrongway around]

i do not know johns turbo numbers , and no i am not running an aussie turbo. this one is designed and built in vancouver. the point i am trying to see is the fact that ,my power is not from my custom turbo,but from fuel pump tweeking and improved air flow via an intake manifold mod. bottom line is i am trying to keep my truck pretty much in the class of backyard builds ,where an average guy after a proffesional pump tweek tune can build and maintain on a dime budget , locally.

 

[ForealBoreal]

i do not know johns turbo numbers , and no i am not running an aussie turbo. this one is designed and built in vancouver. the point i am trying to see is the fact that ,my power is not from my custom turbo,but from fuel pump tweeking and improved air flow via an intake manifold mod. bottom line is i am trying to keep my truck pretty much in the class of backyard builds ,where an average guy after a proffesional pump tweek tune can build and maintain on a dime budget , locally.

that is awesome.
Really cool to hear that guys are doing local extreme valve body upgrades with a place in Vancouver for a fraction of the cost too.
Would love to see a few shots of your 81s engine bay.

 

[sailor]

I don't think cost is the major factor, immediate local support is more likely the motivator.