Dual IHI Turbos on a 300 six

B

BIG 6 farmer

Well-known member
This came up in Truck Engine section. Are dual IHI turbos off an 87-88 Turbo Coupe, too much for a low speed turbo 300 six ? ( 1800-3500). I know someone has done it. Dug out a Hot Rod Magazine, June 2001 page 21. A 57 Mercury Wagon. 472 Ford ( .o6o over 460 ) Dual Garrett TO3Es, off a 86 T-Coupe ( yes theyre a little bigger). Full Boost by 2200. 355 H.P. @ 4200, 713 lb.ft. @ 2200 . This tells me the IHIs on the 300 six would boost @ a higher RPM. ( 3000-5000?) I know this is all shoot from the hip.
 
Engine speed has pretty much nothing to do with anything. Turbos "consume" airflow and produce airflow. Their performance is dictated by how much exhaust goes in and how much air comes out. Given that the 2nd gen TurboCoupe was a 140ci motor and the IHI was plenty responsive in that environment, I think it'd be reasonable to assume that 2 IHIs would be decent on 300ci. However without knowing what type of power you want to make (and thus what the required CFM and boost pressure you need) it's impossible to know whether it's truly a good match. That said, twin turbos on an inline motor are generally considered unnecessary complexity these days. You're almost universally better off with a single, proper-sized turbo. Hell, BMW is pushing the idea that twin turbos on a V engine is less than ideal!
 
I used one IHI5RB turbo from a Mazda 626 Turbo on my Cologne V6. The turbo was a standard small turbo, sized for about 150 hp in single applications, and considerably more in BiTurbo applications.

It won't give you any problems at all, and they are small in single form for anything more than a stock 4.9 tootling along.The Maseratii Bi Turbo used two of them with just 121 cubic inches.

The dual out let EFI header is a perfect set up for them. Who cares if a single may be better when the IHI's were shoved out on almost every Turbo Japanese car ever made, and it was GM's chosen turbo for the Citation 660 Turbo. The little bu99er is very common.
 
Are there compressor maps available for the various IHI models?
Plotting your airflow and boost on a map is by far the most accurate way of sizing a turbo for a given application.
 
Here's an interesting turbo specifier' with popular turbo maps , a few IHI:

http://www.squirrelpf.com/turbocalc/



I haven't looked at 300 applications but optimum 200/250 applicable turbo map's are still unfolding to me. The turbo's map's that seem optimum to me, require a better understanding of tech-jargon and expectations.

Understanding the maps for available turbo suitable for 200/250 track/street build is exactly what I'm needing for help with. There are maps available for most popular turbo's if you look in vehicle specific forums but it seems suitable turbo for six's may be out of mainstream availability or map references. Some biggest IHI (water cooled) used on WRX/STI?.,


helpful info or links appreciated...
 
I don't want to hog thread but is on topic:
The turbo calculator lets you choose Single or Twin turbo's and matches with the maps. Calculator includes displacement, target HP, pressure reference, and a few not sure of including :

BSFC, -?
Max I/C Loss, - ?

RPM Points
Engine Redline: ? (@ 6000)
Peak Power at: ? ( @5500)
Max Boost at: ?
Min Boost at: ?
( CI ) turbo cam specs will determine part of this.

charts like Turbonetics Turbo Matrix mates 250 six with small-end T4 but "hybrid T3/offshore knock-off's" with adapted wheel sizes adds to options.

http://www.turboneticsinc.com/sites/def ... rix%20.pdf

.. so generally the low end-torquey' - limited revving six (breathing starved log 200/250) need a smaller-sooner-spooling or big low RPM diesel type ?.

Any recommended specific model turbo's and maps applicable to study appreciated...

thanks
 
If you click on "more" next to BSFC, it will tell you what it means and what value to enter
Max I/C loss is the pressure drop across the intercooler. Use their default value until you actually size the I/C

For the RPM points, just put in what you'd like those values to be
Just to check out the calculator, I used 4000 for redline
3400 for peak power (same as normally aspirated)
2000 for max boost (i.e. the point at which you want the turbo to be completely spooled under load at WOT)
1200 for min boost (the RPM at which you want it spooled down

More critical by far are the volumetric efficiency numbers. On a stock 300 they are very low, around 65% at 3400 and up, about 70-75 at lower RPMs then back down to 65% below about 1500. This is why the 300 needs head work
 
thesameguy":1n9x7ga9 said:
Engine speed has pretty much nothing to do with anything. Turbos "consume" airflow and produce airflow. Their performance is dictated by how much exhaust goes in and how much air comes out. Given that the 2nd gen TurboCoupe was a 140ci motor and the IHI was plenty responsive in that environment, I think it'd be reasonable to assume that 2 IHIs would be decent on 300ci. However without knowing what type of power you want to make (and thus what the required CFM and boost pressure you need) it's impossible to know whether it's truly a good match. That said, twin turbos on an inline motor are generally considered unnecessary complexity these days. You're almost universally better off with a single, proper-sized turbo. heck, BMW is pushing the idea that twin turbos on a V engine is less than ideal!
Click to expand...
you miss the point of the question. Its what RPM you will have the boost? In a low speed truck ( 1800-3500 rpm ) Im thinking i will use a single Garrett TO3E on my Bus with a 300 six. Because i have one, that i can use as a starting point. With out looking up a Compressor Map, i think i will be close.
 
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