Dyno - 12cm2 vs 16cm2!!!

[Matt S]

I finally got the chance to do as best apples to apples comparison as I could. Differences - a little cooler, winter fuel, housings. Total peak horsepower for 16 cm2 was 229. 7 (between 55-60 mph). For 12 cm2 it was 225. 7 (between 56-59 mph). A difference of 4 horsepower at 55-60 mph in 4th gear.



From my dyno graphs



mph 12 cm2 16 cm2 Diff (12cm2-16cm2)

30 85 hp 80 hp +5

35 112 hp 105 hp +7

40 155 hp 140 hp +15

45 195 hp 187 hp +8

50 212 hp 212 hp -

55 221 hp 225 hp -4

60 223 hp 228 hp -5

65 163 hp 175 hp -12

70 65 hp 75 hp -10





The EGT's were about 100* higher with the 12cm2 at 900* Boost was not the same as on the street as the dyno doesn't load up the trucks that well.



Driving impressions- The truck FEELS like it has more power than before. I now have traction problems due to the quick boost build up. I have yet to tow with this housing in the summer but I don't have any EGT problems at my current fueling level. The fuel was the same with both housings. I like the 12cm2 housing as I feel it gives me power in the area that I use it most. I drive in city traffic around Boston.

 

[drives mopars]

great

i never did this comparson

but was at 215 hp before i turned up

on mustang that was 20 hp lower then other\dyno



so close to 250 hp in the 93



have the 14 cm fueling temps go to 1250



1 ton 4x4 bill

 

[Power Wagon]

Originally posted by Matt S



mph 12 cm2 16 cm2 Diff (12cm2-16cm2)

30 85 hp 80 hp +5

35 112 hp 105 hp +7

40 155 hp 140 hp +15

45 195 hp 187 hp +8

50 212 hp 212 hp -

55 221 hp 225 hp -4

60 223 hp 228 hp -5

65 163 hp 175 hp -12

70 65 hp 75 hp -10

Do you have some sort of rpm / mph correlation? This is most useful when stated in RPM, and not MPH. I'm going to switch from the stock 93 (18?) to a wastegated 12.



Also, did you try reducing the boost level at which the wastegate opens? That may help. If you're running more boost than the 16 housing did at 2500, then you could dial it back to the same, which should result in far less parasitic HP losses due to drive pressure concerns.





Was this done on an acceleromoter like the dynojet, or on a constant speed dyno?

 

[R.E. Miller]

Hey Matt,

Nice R&D work! Quick question, where are your fuel screws on your pump set to? Just trying to see what I'll have to do on my truck.

Thanks,

Russell

 

[JFitzgerald]

Great info!

This is great since I have been thinking about a swap to a 12 or 14 cm housing. Did you happen to get a torque number comparison also? Looks like a 12 would help in getting my load moving, but may hurt a bit when I hit a big hill at 60-65 mph. Maybe there are torque gains that would override the small HP loss??



Thanks.

 

[Matt S]

Answers to questions

I don't have my fuel maxed as I don't want to worry about EGT temps or cracking the head as some of the non-intercooled 1st Gens are known to do. I want SAFE power that I can use anytime. This is why I only see between 800-900* on the dyno. I have the pump turned up about 1. 5 turns and the AFC turned 90*. I do have smoke but it clears up with the 12cm2 housing. The dyno is a dynojet. I start off at idle in 4th gear and floor it until I lose boost at 2700-2800 RPM. The truck is in direct with 3. 54 gears. I the print out isn't in RPM and there are no torque figures. They are getting an optical sensor so that we will have RPM's and torque in the spring. The 60-65 mph load on the hill would be in the sweet spot at around 1800-1900 RPM. The difference is in the power after the shift point in the lower RPM's.



I have weighed 12,500 lbs combined and never had to downshift when I hit a hill at 70 mph. This included Rt 77 from North Carolina to Virginia. All this was before ANY mods to the truck. I think this set-up would be great for towing.

 

[KEENO]

Great Comparison Matt!



I feel that your factual numbers directly compare with my 'seat of the pants' driving impressions. My Opinion on housings has always been... "It depends on how you drive your truck and preferences in powerband characteristics".



What your numbers show is that if you're looking for the perfect housing with the least amount of compromise... Maybe the 14cm2 gives you the best of both worlds.



Even with seeing the "top end" loss of the 12cm2 in 'hard numbers'..... I'm not willing to trade off the 'increase' on the bottom end. I like the 12 for the way I drive!



Great stuff Brother!



KEENO

 

[KEENO]

Winter fuel?

Hey Matt!



I went back & read your original posting and was wonder your thoughts/opinion on the impact of "Winterized Fuel" on the comparision.



I know after driving my truck through the winter months that I can really tell when I get my first tank of 'pure' #2 Diesel in the Spring. It always brings a smile to my face!



I know this is a speculative question but was curious of your thoughts.



KEENO

 

[NOMOFO]

I've just joined the 12cm club and am hooked. I have another turbo with a 16cm that I'm likely to put on for long trips with the camper. After trying both I'm hooked on the 12cm for my daily driving. I have yet not touched anything else as far as pump, exhaust, intake or injectors. So otherwise stock.

I still find a bit of lag right off the line but get up to 1200 or so and up to about 1800 there is all the difference in the world. I suppose I need to fuel up a bit to get that immediate boost. Or maybe something is up with pump or transmission or???

Plans are to first build new exhaust (need one more 90 deg. piece). Then have pump checked and timed up to 1. 45. If it's bad then hello Piers or Diesel Dynamics. Then the mighty Lucas injectors.

Why is this so addictive?

 

[JFitzgerald]

Re: Answers to questions

Originally posted by Matt S

The 60-65 mph load on the hill would be in the sweet spot at around 1800-1900 RPM. The difference is in the power after the shift point in the lower RPM's.

You're right, I was just looking at the chart again and realized there is another gear. In 5th, the power should be right for 60-65 mph towing. I tend to use the low-end grunt when I drive, so I feel the 12 is right for me. I never rev the engine much when going through the gears.



Thanks Matt, you have helped me make up my mind to go with the 12.

 

[Matt S]

Winterized fuel gives less mileage. I'm not sure about the power but if it isn't giving good mileage then I would think the power is not the same but I have no proof of that other than MPG.



NOMOFO- If you take the cap off with 4 screws and turn that 90* clockwise, you will gain bottom end power.



I don't rev it much past 2200 RPM. Usually drive around 1500-1600 RPM. However, I have yet to tow with this housing so I don't know what the EGT's will be. I may have to hook up the waste gate.

 

[R.E. Miller]

NOMOFO,

Another option to consider is to just pull the cap of the AFC housing and loosen the lock nut and turn the screw in there even 1/2 a turn to start until your low speed boost lag goes away. I did this on my dump truck that has the 16 on it and just 3/4's of a turn helped a lot



Joining the 12 club soon!!

Just ordered the down pipe from BD can't even wait, 2nd day air too, The TDR will make me need a handicap tag yet.

 

[NOMOFO]

Thanks Matt and R. E. , I've been chicken to tamper with pump to this point and was just going to leave it alone and run the Lucas injectors. But I have been reviewing lots of the pump adjusting posts and downloaded and printed all the stuff from D. Fritz. I have a really big itch now! I guess if it blows I would have to suffer with one of those 230's! Maybe my wife will get me one for a stocking stuffer.

 

[drives mopars]

mine went

i had pw's and still more to turn on pump

had 14 cm was great



all this no more its gone !

 

[Matt S]

Pump adjustments

I too was nervous about the pump adjustments. But with the injectors and some info from another member stating that a modest adjustment would reduce the life by 10%, I did it and wouldn't put it back. Truck just is even more fun to drive with the smoke and power. Just get your screwdriver out and give it a little twist.

 

[KEENO]

Apprehensive?

No Worries!... . On adjusting the pump!



If you take your time & mark all of the original positions... . It can be returned to OEM specs @ any time.



Do some reading, understand the unit & have some goals in mind. Make one adjustment at a time & evaluate... Take some notes... Make another adjustment... . Smoke & Smile!



KEENO

 

[NOMOFO]

I think I'll take up smoking soon! Yeehaw! Finally made 100 posts! Think I'll have a drink immediately!

 

[Mopar-muscle]

question for a non member .....

friend of mine has a 91. 5 5 spd , what housing is on his turbo ? he's been lurking and thinks he wants to change to the 12 housing .



thanks from an overvalved brother ...

 

[R.E. Miller]

Mopar-muscle,

I think that the 91. 5's had the 18. 5cm^2 housing from the factory. My 92 has the boat ancor of the group the 21cm^2 Either way, the 16cm^2 housing will help a ton, but I want to see what a 12 can do. I might have it in on Sunday, Ill post my new #'s then.

Russell

 

[BushWakr - RIP]

Housing size should also be there as part of the casting (I think )

My experience with the change from 18. 5cm to the 16cm was not as impressive as I had hoped. It is a good housing, it does give you a bit quicker spool up and I do see about 1 1/2 - 2 lbs more boost but just not "WOW" difference. Going from 21 to 16 would be very noticable. I'm gonna get myself the 14 NWG'd from Piers after Xmas.

MHO



Merry Christmas, Bob