Twin Charged Alfa 33 calling Madmac666

[Alfa33Phil]

Dear All

Following on from Madmac 666 and his efforts with his Evo, I have completed a twin charge build on an Alfa33 16V. Sadly whilst road tuning last week I had a head gasket let go and this weekend I will strip down the heft hand head to inspect.

I have a TD06 20Gturbo flowing into an Eaton M45 and from the little driving I have done whilst tuning I am impressed with the drive ability. My question to Madmac is what static compression on the evo do you run ? I have a static 9.3:1 ratio and am considering a lower ratio for safe boost on 93 RON. I am in Sydney, Australia

regards Phil

 

[madmac666]

Phil, it's always good to hear of others trying twincharging and I get contacted by many throughout the world who have been inspired by my evo project which is still going great and being developed all the time. To be fair, I am relatively new to twincharging and I learned a lot from warpspeed on the forum who has more experience than me with twincharging. Having your own designed system is a learning curve for sure

I run a compression ratio of 9.8:1. Perhaps a bit high for the boost we are running but our ignition advance is still a few degrees more than we had at the same boost with a turbo only. The efficiency of a well setup twincharger allows a slightly higher comp ratio to be used as there is less heat produced pre-spark due to the reduced exhaust gasses present for the intake stroke.

9.3:1 is ok for a reliable boosted engine , you may see benefits increasing this to 9.5:1 though - unless your head gasket failure is due to excessive cylinder pressure. Have you analysed the gasket to find the reason it failed? Head lift is more likely on a compound setup at high boost so I would recommend a very high spec stud fastener to hold the heads in place.

What combined boost are you achieving? I have to admit I know nothing about the Alfa V6 engine or its weaknesses/strengths. In general your compression ratio should be of no concern

 

[Alfa33Phil]

Dear Madmac

It's very early days yet in respect to boost as I was still doing basic fuel tuning on the road when the gasket went. I am yet to pull the heads off to determine what happened but I know I have a failure in the gasket as coolant was disappearing and the temperature was soaring. Hopefully there is no problem with piston and rings. The engine is a 4 cylinder boxer engine bored out to 88mm (1768cc). It has standard 16V rods with forged pistons. The head to block bolt pattern arrangement is very sturdy. I am relying on the better quality factory gaskets (Reinz) that are available to do their bit. The static compression is 9.3/1 whilst the dynamic compression ratio is 8.4/1 therefore I will probably leave the compression as is and get a tune with 98RON and maybe trial E85. The ECU is a Haltech sport 1000 and this ECU allows plenty of scope for dual fuel/spark tables, boost control, water injection etc. I am using throttle position v RPM as the main load for fueling with MAP compensation because I have multiple throttle bodies.

I have run the car turbod (TD05 16G) for the last two years including two sprint events. With water injection the car was up to 300 HP with an average tune. I have gone twin charge to see what I can achieve in low/mid range performance rather than achieving a large peak HP. For a FWD car weighing in at 1080kg it's a fun car around the bends in the wet and dry.


I was seeing 5-7 psi of boost at 2500 rpm and the torque right from down low was awesome. I was barely opening the throttle after this as there was so much air being shoved past the 4 individual throttle bodies. I should have exercised more discipline in respect to timing and getting the car on to a dyno immediately for spark tuning rather than fuel tuning on the road. I am certain I will see a fantastic torque curve through to 6800 rpm. After adjusting the fuel maps from 1200 rpm up to 4000 the car sure was getting thirsty. The air flow is as follows... intake/turbo/supercharger/chargecooler/25mm BOV (3 psi spring)/ 4 x throttle bodies. I had another chargecooler after the turbo but I have removed it as I felt it was too restrictive. I am envious of the room that the Lancia S4 has as 2 huge air to air or at least water intercoolers would be great.

I have based the turbo sizing on the advice from yourself, Warpspeed and others. The larger turbine A/R and lower pulley ratio for the eaton M45(4 psi) seems to initially have been spot on for the engine size. My number one enemy will be heat as I am seeing an increase of at least 20 deg centigrade across the board compared to running with the turbo alone. The little m45 (no room for an m62) is going to be producing plenty of heat due to it multiplying the output from the turbo. I am running water injection pre supercharger to assist with temp control.

All Intercoolers, brackets, manifolds on this engine I have designed and built myself as nothing exists for this car. I am severely restricted in space and therefore the air water cooler is tiny. I have previously had great luck with various combinations of water/meth and I feel I will also have to inject post intercooler/pre throttle bodies for intake and in cylinder cooling. I will also add another blow off valve after the turbo to reduce flow into the supercharger during low manifold pressure events.

regards Phil

 

[1gibson]

Water injection before a roots blower will increase the parasitic losses, which are already "off the charts" because it is moving compressed air. Pros can outweigh the cons if the blower is your only power adder, and the VE increase (fluid helps seal rotor to case clearances) can be worth a little extra parasitic loss. But too much volume and things go downhill. Too much fluid through the blower will slow you down.

Since you will have it apart anyway, hit the rotors with a spray bottle of water and do before/after "spin test" by hand, see what you think.

 

[madmac666]

Phil, At first i thought i didn't need a cooler after the turbo but once we pressed on and increased boost it became apparent that although the system didn't suffer too much, the heat of the turbo charge air was getting high enough to cause the blower some issues in terms of thermal expansion. Eaton specify 50c as the maximum 'safe' intake temp for the HTV, not sure what it would be on the M45 unit. The other thing to consider is the higher the intake temp to the blower, the higher the outlet temp will be so the intercooler you have will need to be bigger to take more heat out before the throttle bodies. What I found through the development is the colder you can get the inlet to the blower, the denser the air being multiplied will be which is beneficial for power production everywhere in the rev range. Since your intake temp is up 20c, i'd be looking at a way - any way possible, to install a chargecooler after the turbo. This will benefit your setup in a few ways - safer for the blower, denser charge and feed your intercooler with cooler charge which in turn will lower your inlet temps and allowing more ignition advance. There's always a trade-off with cooling but generally the cooler you can get your charge into both the blower and the engine the better.

With throttle bodies, I assume you have some kind of bypass around the blower, or a pressure dump to unload the blower when the throttle butterflies are at low openings, such as cruise?

Over the winter i removed my water/air chargecooler system, all 40Kg of it and built a bespoke intercooler which gets it's air from the front of the car. It was back on the dyno on Saturday and we are seeing no more than 24c into the blower with an ambient temp of 16c on the day. This allowed us to see the same 850hp but at 2.5bar boost instead of the 2.75bar we needed last year. This is mostly due to the lower charge temp into the blower. Water/meth injection in my mind complicates things, it's always better to cool the charge with intercoolers if possible but if setup right, injecting water is also going to benefit the engine. There's a fine line in getting it right so it's problem free. Water will tend to condense on the inside of the intercooler core if not metered properly.

For your head gasket, it may be worth considering wire-ringing the heads. We have done this to our engine which has improved reliability but until you have checked the evidence from your failed gasket it's only speculation as to whether you need to go to that extreme.

 

[thundair]

Isky has an ‘o’ ring grove tool that is used by hand
They rent it out for 60 bucks I have never used it but the fact that it is a responsible company and that it is still available says something

http://www.iskycams.com/onlinecatalog.html

plus Isky Accessories plus o ring

Cheers

I don't know anything but the people that do.

 

[Alfa33Phil]

Thanks to all for your input. After stripping the heads off I luckily only had a pushed out head gasket with no damage to pistons/ rings etc. So the engine is in and I will run it up normally aspirated before taking it to a tuner. I want to add another intercooler after the turbo but packaging is very difficult. I did have another charge cooler in place after the turbo but it was very busy trying to run two charge coolers. I am thinking of adding another water/ meth jet after the charge cooler before the plenum to assist with charge cooling and in cylinder cooling. Currently I am injecting into the supercharger inlet.

I haven't had a chance to trial belt loads on the supercharger and to look at the pros/cons of water injection into the supercharger. I did notice however an average drop of temps while under boost when the spray was running.

Can any one comment on what size bypass/ blow off valve they are using in their setup. Remembering the flow in my setup is as follows.... Filter: turbo: Eaton M45 (with no factory bypass): charge cooler: plumb back bypass valve :4 throttle bodies: combustion chamber. I am currently relying on a turbosmart 25mm Kompact plumb back Bypass valve. It has a 3psi spring that at part throttle and idle, opens fully to release all unnecessary pressure in the manifold. I have it routed back into the system behind the air filter to reduce the bypass noise.

I am wondering if 25mm is too small and that I should really be adding another 25mm unit in parallel or a large BOV such as a Tial QR. Does anyone have views on whether I need another bypass valve to be placed between the turbo and the supercharger to reduce the compounded overall pressure seen at the manifold. I am thinking that anytime at decel and part throttle (when dumping unwanted boost) it would be of benefit to reduce any air flow to the supercharger so it is not compressing and heating air.

Thanks and regards.

 

[Alfa33Phil]

Dear All

Just a quick note to say thanks to all above for their help. The twin charge set up is running superbly. What an awesome torque curve. I have 390 nm of torque at 5000 rpm, with a lower peak HP of 190 FWHP. I am now adding a 5 x 6 (barrel air/water) after the turbo as I am timing restricted due to detonation (heat) when the turbo spools up. I am sure the water injection is assisting beyond 4500 rpm. Target wheel HP is where it was with turbo alone at around 280/300 HP

The only bypass I have is essentially a 50mm blowoff valve with a 3 psi spring that opens to dump both the combined output of the eaton and the turbo together. It is located after the eaton and before the air water intercooler. The driveability is great with only the slightest flutter during transition form on to off boost. I hope to get some videos up at some stage. If anyone has any questions feel free to get in touch.

A question for Madmac and others..... has anyone undertaken tests on turbine back pressure to inlet ratios? I am seeing 22psi of pre turbine pressure to 18 psi of manifold pressure.
cheers P

 

[Alfa33Phil]

Whoa big mistake in my power figure there.,,,

torque hit 385 nm @ 4730rpm = 347 HP corrected
torque peak 390 nm @ 5079 rpm = 377 HP corrected before falling off to 360 nm at 5510.

As mentioned I fitted the 5 x 6 PWR intercooler after the turbo and the top end butt dyno tells me there is no drop off after 5000 rpm. I am sure I am around the 400 HP mark at 6000 rpm or so. Wheels spin easily in 3rd gear at 5000 rpm especially when the plenum is not heat soaked. I have also added bonnet vents and exhaust wrapped the turbine/CHRA.

I am experiencing large heat soak into the compressor of the turbo (prior to wrapping) and will try to fit the old 25mm Kompact BOV after the turbo compressor to see if surge between the turbo and the supercharger is creating heat.

cheers P