Twincharging - calling Warpspeed! 3

[madmac666]

thread71-174690

Hi guys, i subscribed to this forum because i found the thread (referenced above) on twincharging while doing a Google search for information on this subject.

I have to say, the thread and contributions from forum users was very good and informative, which gave me a direction to follow for my own twincharger build.

Some background on this: I have a 1997 Mitsubishi Lancer Evolution 5 which i've used for sprints and hillclimbs in Scotland for a few years now. The state of tune of the car is such that we were producing around 650hp, but with the big turbo at 2.6bar, lag was always an issue. Twincharging seemed the most sensible option for the car to eliminate the lag and hopefully produce a torque curve with spool much lower in the rev range.

I'm using a Harrop HTV 1320 blower and the existing turbo which is a hybrid T04Z with 0.82 housing. This is the turbo that gave us 650hp previously, but on a 0,63 housing. The system is compound compression with the turbo feeding the blower. The blower has a 75mm pulley and the crank 150mm pulley so a ratio of 2:1.

I have the blower mounted and all pipework finished and finally had her on the rolling road a few days ago. We saw some impressive torque figures but had to cut the session short due to belt slip on the blower pulley when the turbo reached 1.5bar. The system i have uses a 32mm toothed belt but the length of the belt seems to be an issue as it's stretching and allowing it to jump over the pulley when the turbo spools up. We also had issues with controlling the turbo boost and decided i need to install another wastegate to allow better control of the boost. I'll have that done by next week RR session so we have control of the turbo boost and can carry on mapping.

It seems the belt starts to jump when the turbo reaches 1.5bar and the drive simply cannot cope with the power needed to increase boost by a factor of 2. I have a larger pulley (100mm) which i'll be fitting over the weekend and hope the longer wrap around of the belt on the larger pulley and the reduction of the drive ratio should sort out the issue of the drive. If it doesn't then i have another modification i can do to run a shorter belt on the blower and split the ancilliaries onto 2 separate belts but i'd like to try this again with the reduction in drive frst before i go to the trouble of a re-design of the belt drive. Space is at a premium so 32mm is the widest i can go and still have a chassis leg...

We never went above 4000rpm. Despite this, we saw 460ft/lbs torque and 360hp at 4000 and 2.9bar which confirms there's definatley power to be made! Obvously slowing down the blower will mean the turbo will need to be producing more to reach our goal of 2.5bar total. The outlet temp of 80c from the turbo at 1.5bar was logged, which is about the limit of the blower seals. I hope to keep the turbo around 1.5 bar so the outlet temps don't fry the blower seals. The combined air then goes through a very good intercooler and reduces the final temps to 16c (this is Scotland remember....!) at the plenum.

I think we're almost there and hope to have it mapped on the larger pulley with the extra wastegate fitted for turbo control. Looking at the RR graphs and data we collected the other day, we monitored the pressure from the turbo and combined total and can clearly see a multiply of the turbo by the blower very close to 2:1 from 1800rpm to 4000rpm but we couldn't control the turbo and it looked like it would have carried on climbing which would have killed the engine or the blower.

Because the engine already had the big turbo and supporting mods to make good power, we hope to see some good figures once the issues are ironed out. The engine itself is built to produce 1000hp 'reliably'.

I would like to hear any views and comments on my findings so far. I had considered swapping the turbo and blower order to reduce the power needed to drive the turbo but i felt the extra restriction on the exhaust (because the turbo would be working harder than it used to) would likely end up making less power, as the exhaust back pressure would then be much higher. It would certainly reduce the power needed by the blower


Thanks for posting the useful information, it really was a huge help and if you have anything to add that could help us, i'm all ears!

Donald

 

[bigjuicesr20]

Thanks for the valuable tips. I'll try to use steel pulleys but may use aluminium pulleys if readily available. This car will be mostly used for track/dirt with occasional road use so wear on pulleys is not an issue for me.

Tony,
BTW, I've acquired a few SC's for my various projects. 3 Whipples and an M90. :-D

 

[madmac666]

That's a hell of a project - 4 superchargers!

 

[HRHtex]

Madmac - Slightly off the point here but with cogged rubber cam timing belts I thought they were always locked in place - not just relying on the spring for tension?

 

[PorschaTwin]

Sorry for the OT but I could not find how to PM!

"I have an Audi 5 cyl Coupe Quattro and have a couple SC's I can use for this project. I don't care about belt noise levels as I'm just going to rally/auto cross this car. I just don't want belt slippage."

Bigjuicesr20,

I was planning something similar on the 5 pot Audi. Where were you thinking of placing the SC? I was thinking under the inlet. Would love to share info and even some development.

Cheers

 

[madmac666]

Although the tensioner is spring loaded, this is because the OEM one is setup like this. I modified it so i could lock it tight once in position - read my post above...

 

[Warpspeed]

Where to place the blower ?

Usually wherever the great enormous thing will fit.

They don't usually look that large in photographs, or even the engineering drawings.
But once purchased, and sitting on your work bench, they kind of grow in size.

Sitting loose, and balanced on top of your valve cover, and looking at the available (?) space around the engine, the reality of the true enormity of the thing is going to hit pretty hard.

Almost every blower installation requires several other things to be moved to make room, and that is what complicates things.

 

[madmac666]

I agree, they always look smaller in photos!

In my installation, i had to cut the flange off the alloy fabricated inlet manifold, tilt the plenum to 15 degrees and weld the flange back on then skim the flange again. This just gave me enough room to fit the SC below the manifold behind the engine. The chassis leg also needed a small section cut away for the drive pulley. The SC now sits less than 1mm from the water pump with the bypass actuator 2mm away from the engine block. This all had to be achieved while still allowing for access to the transfer box top bolts! It's very tight in that space but now looks almost OE fitment. Also think about weight distribution. If you can install it on the opposite side of the engine from the driver, and back as far as possible - this is the racer in me thinking out loud!

Weight is the enemy when it comes to competition which is why i hope to lose some myself soon - i'm not a small guy!

Have a look at this article our local newspaper did on the car a few months back:

http://www.pressandjournal.co.uk/Article.aspx/1800463?UserKey=

 

[PorschaTwin]

Great article. That is the first time I have seen pictures of the engine bay of your car. Would love to see more of the installation of the SC etc?? Please??

 

[bigjuicesr20]

"I was planning something similar on the 5 pot Audi. Where were you thinking of placing the SC? I was thinking under the inlet. Would love to share info and even some development."

PorschaTwin,
Not sure where I'm going to squeeze it in but like Warpspeed and Madmac says the SC looks small in pics but it'll be a challenge to find room in engine bay. I don't need AC so I'm pulling compressor out I don't mind removing OEM intake manifold and making custom one. That small radiator inside engine bay may have to be moved as well. I'm gonna butcher this car to make it fit!! LOL.

 

[bigjuicesr20]

Nice article Donald! Would love to go to UK to witness one of those hillclimb events. Sounds like loads of fun.

Here in the US the closest one I know of is in New Hampshire on Mount Washington.

http://www.climbtotheclouds.com/

A 5 cyl Audi has the record but Travis Pastrana in a built Suby just missed record this year. Bad weather prevented him from 2nd run. even though this Suby is professional sponsored and fully race prepped it can't touch the torque numbers your Evo is putting down. They'd freak if they saw that dyno graph. From 2800rpm to 5500 is just sickness!

If you get some sponsors you need to ship it over here for next years run. )

As PorschaTwin asked could you link us to some engine shots of Sc and pulley setup? I like the idea of using a timing belt and tensioner. BTW, how wide is the belt you're using?

 

[patprimmer]

Pikes Peak is supposed to be a pretty good hillclimb event in the USA

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[TDAA]

Pikes peak also gives you a nice mix of asphalt and gravel (until they complete drainage improvements and paving).

http://www.usacracing.com/ppihc

There are some tight hairpins with big drops off of them. It is a good drive, but not being a racer, I think it would freak me out to drive that road really fast.

 

[Warpspeed]

It freaks ME out just watching Pikes Peak on TV from an onboard camera, that is one very serious hill to climb at speed.

 

[PorschaTwin]

To the experts on here: If this project was repeated on something very similar (and I am tempted!), what would a good choice of SC and turbo be for 750bhp on a 2.1L motor? Eaton M90 & GT40R?? Should I be thinking of approx half boost from the SC and half from the turbo?

Anybody tried this calculator from Supercharger Performance?
There is a twincharger calc so I will have a mess about with it!

 

[WhizzMan]

Someone directed me to the site of the Lancia EV1. Since it's in Italian, I put the translate link of it here.

http://translate.google.com/transla...e=UTF-8&layout=2&eotf=1&sl=it&tl=en&u=http://

http://www.ecv1.com/home.htm

 

[WhizzMan]

After some more reading, it turns out that the predecessor, the Lancia S4 had twin charging, the ECV1 has 2 turbo's.

 

[PorschaTwin]

I posted this a little while back but no response:

"To the experts on here: If this project was repeated on something very similar (and I am tempted!), what would a good choice of SC and turbo be for 750bhp on a 2.1L motor? Eaton M90 & GT40R?? Should I be thinking of approx half boost from the SC and half from the turbo?"

Any pointers please?

 

[Warpspeed]

An Eaton M90 would probably do it, though it would not be my first choice.
Take a look at the much newer Eaton TVS range of superchargers. They flow much more air at both ends of the range, and with much higher thermal efficiency everywhere.

The rather special Harrop blower Donald is using is an Australian upgraded version of one of these Eaton TVS blowers. These are still a roots style blower, (not a screw blower) but are designed for the very high airflow required these days on modern high output V8 engines. An M90 simply cannot breathe as well at the top end as a TVS.

Again, a large size GT40R would be a quite reasonable choice for that power range, but the TO4Z would have a considerably wider flow range at both ends.

I guess it depends upon your budget.
The M90 and GT40R would certainly be workable, but Donald's much more expensive combination of blower and turbo would make that top end power range a lot easier to achieve, and also be more responsive down low.

 

[PorschaTwin]

Thanks Warpspeed. I was not aware of the Harrop blowers. I assume they are OE fitment on Holdens or something similar? I don't like the idea of the internal bypass - I would like to keep options open by using an external type.

As for the new Eaton TVS type, are they available from any UK production vehicles or do they need to be purchased from Eaton? Are they still known as M90, M112 etc?

If I need to buy a new one, should I go twin screw with a Whipple? I have a couple of 140AX blowers for another project.....

Thanks again.

 

[Warpspeed]

I agree an external bypass has quite a few advantages over the standard internal Eaton butterfly setup.

I am from Oz, so remain blissfully unaware of what production vehicles in the UK are using.
The just announced new Australian FPV supercharged Ford V8 uses the Harrop blower.

If you google "Eaton TVS" that should get you started with some info, and tracking one down locally.

Buying new opens up quite a few possibilities, and the price differential for the various types and sizes is not that great, so you get to choose exactly what you want.
Buying secondhand limits you to the much older designs, but at a huge cost saving compared to new.

Comparing a Toyota SC14 to a Whipple M90, to a screw blower or a TVS is like chalk and cheese. The technology and performance difference is immense.

Similar to comparing a fifty year old diesel turbo with sleeve bearings and very heavy and crudely designed wheels, to a modern ball bearing turbo.
To the uninitiated they appear to look pretty much outwardly the same, and do the same thing, but they sure are not the same.