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Well finally got some actual back to back testing with t4 vs our new KC300x Gen 3 turbos and thought we would share the data. We un-t4-swapped a 7.3.
The opportunity arose because Matt @ gearhead was having some issues with his truck. He did a very nice build but it did not end up the way he wanted. It was a little smokey/laggy down low and overall ended up very disappointed and didn’t drive the truck very much. We offered to take a look at it for him so he shipped his truck out to us from TX to AZ and we started diving in.
2001 7.3 with full built motor, ported heads, cam, piston work, headers, 238cc/80%, and s364.5/73/.91. We got the truck in and was worried it might be an injector issue or maybe mismatched size because they just seemed to flow too much down low, but made awesome top end power. We sent the injectors to Nate @ Unlimited Diesel and he flow benched them and verified the size and that nothing was wrong. When we got them back we spent a lot of time on tuning, checking for boost/exhaust leaks, driving the truck around on and off the dyno. We were not sure if the ported heads/cam/pistons could because issues and was not ready (did not want to?) to tear into the motor.
We decided to try some turbo options, the t4 setup always fit a little weird, was leaking oil, and the downpipe was causing a huge leak we couldn’t seem to get right… so we decided to take this time to do some back to back testing.
Same tune, just swapped turbos. See dyno pic below for results.
S364.5 – 585hp and 1255tq
KC s2 – 578hp and 1276tq
KC s1 – 563hp and 1281tq
If you look at the dyno graphs you can see the s364.5 carried the HP a little better on top, but came on much later and made less peak tq. The KC s2 spooled about 100-200rpms sooner, KC s1 spooled 200-300rpms sooner. I honestly could not tell a difference in top end power on the street but the spool up was super obvious. The s1 cleaned up all the low end smoke and we were able to make the tune a little more aggressive down low to bring on the power sooner without crazy smoke like before with the T4 turbo installed.
Matt’s goals for the truck were aimed at quick spool up, low smoke, and he said his goal was to only make 500hp, but wanted it to be super clean. So he decided to keep the KC s1 gen3 turbo on his truck and pull some fuel on the top end to bring the HP down.
Would an s364.5/68 have spooled faster? for sure but would have also lost top end power?
Does this mean the KC is better in every way. Nope... but man we are trying to make the best drop in turbos and we won't stop here either.
Does this mean everyone with a t4 kit should swap back to drop in turbo. NO WAY. T4 kits are great and have great turbo options and can go much larger. They have some weird quicks with oil drains/feed and boots blowing off, and some guys prefer the OEM fitment look (especially in emissions states) but I am not advertising that people should un-t4 swap their trucks.
For a little deeper dive into the turbo data we found interesting. The s364.5 ran very “efficiently” when it came to boost/ebp ratios. It was very impressive. But it was also laggy? So efficiency isn’t everything
IMO, it comes down to what you want. Most customers we deal with care most about quick spooling and that was the biggest goal with the new gen 3 turbos. Here is an example of what I am talking about. At 1900 rpms we saw the biggest variance in HP/tq/boost/ebp/etc. So here is just a screen shot of that data
1900rpms 85% load, 3rd gear
S364 375hp 1027tq
20 boost
16 ebp
Kcs2 433hp 1187tq
22 boost
22 ebp
KC s1 448hp and 1227tq
27 boost
28 ebp
We have had customers ask us why we don’t release compressor maps or sizing for our most recent lineup of turbos. They have even gone so far as to threaten to not buy one until they see this data. The real reason we don’t want to post this information is that the all new kc300x Gen 3 is so vastly different from any turbo on the market for the 7.3 powerstroke that these numbers would only confuse the market and we often get copied by people who simply read specs off of our website. What we want to offer is much more valuable and this comes in the shape of towing tests, boost numbers, spool up times, injectors sizing to pair with our turbos and dyno graphs. The most important part of your truck is its drivability. A turbocharger’s compressor map doesn’t have as large of an impact on driving, towing, and spool up than what we want to showcase with this data. By providing data with injectors sizes, tuning options, how they tow, how they spool, how they drive, etc, we are striving to bring you the most complete understanding on how these turbos perform. It is simply impossible to get any of that data from compressor map.
To drive that point home. In a 6.0 or 7.3 making 550hp s363/68 is going to tow better, spool faster, and make more power than an s363/73 even though they share the same compressor map. Also the s363/68 will outperform the new s364r/73 even though its more efficient and has a wider compressor map. Turbine wheel and turbine housing size matters, application matters, efficiency of the motor matters. Injector size and tuning matters, how you are actually able to spool up the turbo and use the power matters WAY MORE than efficiency islands on a compressor map. You just can’t get that info from maps and reading wheel sizes, it takes real world experience and that is what we actually do provide. The info we give about towing, injector sizing, dyno graphs, and recommended tuning is literally GOLD! Its where the rubber actually meets the road in real life, nothing is better than that. Passing on REALY WORLD application data for theoretical efficiency islands maps is NUTS!
I'm a little confused on the 363/68 vs 364 SX-R though. you say the 364 is a 73 but it's a 68, no?.
I'm asking because I recently went to the 364/ 68 for my 200/30's. As with Matt, I am still not completely satisfied and not sure what I want to do. I thought about pulling the T4 and going to your Gen 3...I also question my decision on 200/ 30's vs going with 238/80. I was running 250/100's on 366/73 and 369SXE prior to the switch to 200's. Truck feels like a stock chipped now, but tows better at high elevation. I'll figure something out one day.
Appreciate your time doing all the testing and sharing with us
...I also question my decision on 200/ 30's vs going with 238/80. I was running 250/100's on 366/73 and 369SXE prior to the switch to 200's. Truck feels like a stock chipped now, but tows better at high elevation. I'll figure something out one day.
Appreciate your time doing all the testing and sharing with us
I think you need to run a stock chipped truck for a while to realize how much more the 200/30 and 364 are power wise
Blowing boots, oil leaks and crazy smoke... Sure would be nice to hear what T4 kit Matt selected to go with his built motor. Perhaps it is because my engine is all stock after 267,000 miles, but I don't have any of those issues with my CSD T4 kit.
I also realize the limitations of my 25 year old truck and the reliability concerns when asking it to be a tow pig versus a drag strip truck.
Great info and we appreciate you showing us the data. Maybe one day I will have another 7.3L PSD and can install a KC 7th generation turbo. Most likely though, I will be putting a turbo modification toward a 6.7L PSD or Cummins.
Maybe I will sell all of these forced induction vehicles and find a minty NA C7 Grand Sport to go get ice cream in.
I'm a little confused on the 363/68 vs 364 SX-R though. you say the 364 is a 73 but it's a 68, no?.
I'm asking because I recently went to the 364/ 68 for my 200/30's. As with Matt, I am still not completely satisfied and not sure what I want to do. I thought about pulling the T4 and going to your Gen 3...I also question my decision on 200/ 30's vs going with 238/80. I was running 250/100's on 366/73 and 369SXE prior to the switch to 200's. Truck feels like a stock chipped now, but tows better at high elevation. I'll figure something out one day.
Appreciate your time doing all the testing and sharing with us
With regards to injectors. We have seen the same thing comparing 205/30 vs 205/80. One customer said with 205/80 he had to really watch his right foot and had more power than he needed for towing. But with 205/30 it was dummy proof and never had egt issues, but that to press the throttle much harder. The 80% nozzle is going to dump fuel WAY faster. You would have to look at exact flow data but from my testing I would say 200% faster. So that means 200% less throttle to make the same power. So unless your tuner is remapping the whole throttle pedal then they will feel very differently. In other words... 70% throttle with 205/30 will feel about the same 35% throttle with 205/80 but will both make about the same power.
But with that said timing and shifting also play a huge role in power/egts... but at 30% vs 75% throttle you will be in completely different parts of those maps.
You can make a s364r with 73 turbine wheel. But the point was less about the actual borg part numbes and more of an example of how the compressor map tells very little about the story. I can give a few more examples and many of you have experienced the same thing.
s362/73/1.0 vs s362/68/.83 I can tell you which one tows better, even through the share the sample compressor map.
I actually had a customer in a 6.0 come in with a 63/73/1.0 and leave with a 63/68/.91. The 63/68/.91 was better in EVERY way at his 575hp level, but the 63/73/1.0 was more efficient and ran closer boost/ebp ratios. 63/68 spooled faster, towed better, and made more power on the dyno. Both shared the same compressor map.
I was just making the example and giving real world experience on how littler compressor maps play in showing how something actually performs on a truck. Something you guys do very well here in your Turbo spreadsheet you have been creating on FTE. It takes real world experience and testing to gather all that info... which is more valuable IMO than just comparing theoretical compressor maps and how efficient a turbo would be in that part of the map.
I think you need to run a stock chipped truck for a while to realize how much more the 200/30 and 364 are power wise
yeah probably. It would probably be similar to the change i recently made, I imagine, IDK. I do know the nearly 9 sec 0-60 seems like forever....this is in an econo tow tune; however higher HP tunes don't do much better and surprisingly my AA 65 tune is my second fastest at 7:18 which beats race tunes as well as his own...for whatever reasons
For normal driving, it's been great, but I'm not racing anyone anymore, lol...might even get beat by a dodge now
One day I'll grow up
Originally Posted by Peixinho
With regards to injectors. We have seen the same thing comparing 205/30 vs 205/80. One customer said with 205/80 he had to really watch his right foot and had more power than he needed for towing. But with 205/30 it was dummy proof and never had egt issues, but that to press the throttle much harder. The 80% nozzle is going to dump fuel WAY faster. You would have to look at exact flow data but from my testing I would say 200% faster. So that means 200% less throttle to make the same power. So unless your tuner is remapping the whole throttle pedal then they will feel very differently. In other words... 70% throttle with 205/30 will feel about the same 35% throttle with 205/80 but will both make about the same power.
But with that said timing and shifting also play a huge role in power/egts... but at 30% vs 75% throttle you will be in completely different parts of those maps.
You can make a s364r with 73 turbine wheel. But the point was less about the actual borg part numbes and more of an example of how the compressor map tells very little about the story. I can give a few more examples and many of you have experienced the same thing.
s362/73/1.0 vs s362/68/.83 I can tell you which one tows better, even through the share the sample compressor map.
I actually had a customer in a 6.0 come in with a 63/73/1.0 and leave with a 63/68/.91. The 63/68/.91 was better in EVERY way at his 575hp level, but the 63/73/1.0 was more efficient and ran closer boost/ebp ratios. It spooled faster, towed better, and made more power on the dyno. Both shared the same compressor map.
I was just making the example and giving real world experience on how littler compressor maps play in showing how something actually performs on a truck. Something you guys do very well here in your Turbo spreadsheet you have been creating on FTE. It takes real world experience and testing to gather all that info... which is more valuable IMO than just comparing theoretical compressor maps and how efficient a turbo would be in that part of the map.
Thanks again. I'll say I can hit 1250+* by the time I hit 60 on an 80hp daily tune empty. I have tuning from AA, SDK, and GH. No leaks. If I drive normal, then EGT's are good.
Whenever I get off my lazy butt and get my project truck going, I'll definitely be running one of your turbos. I'll definitely run it all stock to start, so i can get a baseline for everything. I just need to get motivated, poor girl has been sitting for the past 5yrs now if not a bit longer
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