Engine/Transmission (1998.5 - 2002) My Twin Hypothesis

[Diesel Freak]

I think I have setteled on how I want to build my twin turbo system.



For the primary I am proposing a Hybrid HY35 turbo. It will have an HX40 Compressor wheel, an 10cm housing with a 1. 5" diameter wastgate port (twice the size of the stock HX35 or HY35). The wastgate will initially be set to lift off at 25 psi. The 10cm housing will dump into a 4" 90 degree pipe elbow where it will then be routed into a H2E with either a 17cm or a 19cm housing. The elbow will have an external wastgate set to limit boost from the H2E to 10 psi.



With the primary running at a PR of 2. 7, and being fed with 10 psig of boost from the seccondary, I am hoping to get 52 PSI out of the system. This is not designed as a system for wild power numbers, but it should be able to support 450 HP, and spool up to at least 25 psi by 1300 RPM with the ability to swallow enough exhaust gas to keep drive pressure below boost pressure at peak boost.

 

[HVAC]

Some of your points are very much on the mark.



I mentioned a while back that there is testing being done on a twin system using a HY turbo. We'll see where that leads.



Then there is the system I'm sending to Texas next week. I'm hoping for strong towing performance. That and nearly zero lag off the bottom.

 

[Jim Fulmer]

So what is the deal with the oil drain on a 12V for the second turbo, my block has a riser towards the rear that looks like the factory one for the turbo? I think Sled Puller said something about this at one time. I'm being told to do a 12V right you need to drop the pan to tap it and put a baffle in it for that drain to keep the oil off the crank, I don't doubt the persons word but I'm wondering about the riser.



Jim

 

[DHRA]

Your 98 should have two oil return bungs. Just pop the freeze plug out of the aft one.

 

[Sky]

Oo. Keep us updated, this one would be awesome! Oo.

 

[CUMINNTSTRKN]

freak



the only problem i can see is that the 10cm might be a little small to drive the h2e. as a mild hp twin setup this could be a good system.



jim

 

[MCummings]

Originally posted by HVAC

Then there is the system I'm sending to Texas next week. I'm hoping for strong towing performance. That and nearly zero lag off the bottom.

HVAC,,, Would the guys name hapen to be Jeff Prince ?

If so,, he's pretty close to my house (~2. 5hrs)



Merrick Cummings Jr

 

[HVAC]

Good guess Merrick.



The twins I'm sending down are going to a fellow just a ways to the north of you. They have some hills in that area and more midrange should make it easier to charge up those hills without the pyro doing summersaults

 

[michaelmurray]

I think flow calculations need to be done to determine the correct size of the compressors. You can get the formulas for multi-stage turbocharging/intercooling from the book "Turbochargers" at Barnes & Noble or Borders Books.



These are some #s I calculated in an Excel spreadsheet...



Match the PR to 2. 8, RPM = 3200, Compressor Eff = . 72, Intercooling and Aftercooling @ 70% efficiency...



-> Discharge Pressure = 101 psi, Compressor #1 CFM = 1565

Compressor#2 = 690 cfm, Compressor#2 discharge temp= 206*F



From TDR #37, Joe Donnelly gave cfm #s of turbos runnning at 2. 8 PR/72% eff. HX35 ~ 600 cfm, HX40 ~700 cfm, H2E ~750 cfm, HX55 ~ 855 cfm, and HX60 ~ 1300 cfm



It appears a good compressor match here would be HX40 primary and either an HX65 secondary or dual (parallel) HY35 secondary. The difficult part is getting the turbos to spin at the appropriate RPM. What the book recommends is that you use two pressure gauges: one in the exhaust manifold and the second between turbine 1 and 2. The ideal turbine size match would be to have equal drive pressure ratio for both turbines at when both compressors are operating at their desired pressure ratios.



Anyway, if space would allow I like using dual HY35/9cm2 as the secondary turbos. This is effectively a compressor with 1200 cfm and 18cm2 turbine.



Just thought I'd shed some light on the subject. I highly recommend you buying the Turbochargers book @ 150 pgs. It allow people to make analytical evaluations as opposed what "sounds" like it would work.



*Disclaimer - I have homemade twins that are not properly matched. They work great, but I know I could build a lot more power and not choke the engine off if I had the correct turbos. I made this system on a budget using existing turbos I had.

 

[Diesel Freak]

Originally posted by michaelmurray

Match the PR to 2. 8, RPM = 3200, Compressor Eff = . 72, Intercooling and Aftercooling @ 70% efficiency...



-> Discharge Pressure = 101 psi, Compressor #1 CFM = 1565

Compressor#2 = 690 cfm, Compressor#2 discharge temp= 206*F



From TDR #37, Joe Donnelly gave cfm #s of turbos runnning at 2. 8 PR/72% eff. HX35 ~ 600 cfm, HX40 ~700 cfm, H2E ~750 cfm, HX55 ~ 855 cfm, and HX60 ~ 1300 cfm

I just have one question. Why do people insist on using CFM when comparing Turbos? I have yet to see a Compressor map with CFM on it.



the compressor maps I have seen have Compressor RPM, Efficiency (%), Mass Flow Rate, and pressure ratio... not Volumeteric Flow Rate which is almost useless when there is such a drastic change in pressure and temperature of the moving fluid which in this case is air which is compressable.



Mass Flow Rate through the whole system is constant.

 

[michaelmurray]

D-Freak,



The book "Turbochargers" also give the calculation for mass flowrate. In the example I gave, the mass flowrate is 124 lbs/min. The book shows many compressor maps, and all use flowrate instead of mass flowrate. The compressor maps are from Rajay, IHI, Garrett, etc. You can't solely go off of mass flowrate in a staged system because mass flowrate is a constant through the system and all of your staged compressors would be the same size. We know that should not be the case.

 

[Jim Fulmer]

Your 98 should have two oil return bungs. Just pop the freeze plug out of the aft one.



Stack-Jack, Yep you are right, yesterday I had a conversation with Al, Piers's right hand man, the 98 blocks with the bung as we talked about were made for that type of purpose, another drain that works without interferring with the crank, the other thing I didn't know is my block is a high nickel one with extra webing for strength, now all I have to do is find the money for twins... . lol. I have more fuel coming as we speak and I know I need more air and a cam, it's going to be tough to put off a bigger single turbo to try some kinda system out. Most of the twins I have seen or heard of are just too much for me, I just don't need 80 PSI, Thanks again for the info.



Jim

 

[Diesel Freak]

Originally posted by michaelmurray

D-Freak,



The book "Turbochargers" also give the calculation for mass flowrate. In the example I gave, the mass flowrate is 124 lbs/min. The book shows many compressor maps, and all use flowrate instead of mass flowrate. The compressor maps are from Rajay, IHI, Garrett, etc. You can't solely go off of mass flowrate in a staged system because mass flowrate is a constant through the system and all of your staged compressors would be the same size. We know that should not be the case.

I think we are arguing semantics a little here.



Mass flow rate is constant regardless of compressor size.



the only time Mass flow rate changes is in the combustion chamber when fuel is admitted into the system, or there is a boost leak, or you are sniffing drugs (N2O, C3H8).



Volumeteric flow rate changes as the air passes through the compressors and intercooler.

 

[TxDieselKid]

Originally posted by michaelmurray

You can get the formulas for multi-stage turbocharging/intercooling from the book "Turbochargers" at Barnes & Noble or Borders Books.

How does this book compair to Corky Bell's "Maximum Boost"? Also, is the "Turbochargers" book written by Hugh MacInnes?