My turn in the barrel is over......
04-23-2015, 06:19 PM
#108
04-24-2015, 12:25 AM
#110
Former Vendor
I am probably going to wish I hadn't done this.. But I'll try it anyway.
Before you go looking at the stupid freaking, near worthless peak numbers, please note that I have maintained the same RPM range as that of a stock engine while adding over 200ccs to it. This is NOT easy to do as bigger engines tend to inherently move the RPM range down for both Tq and HP.
It takes a lot of time with internal mods to CR, port flow, camshaft timing and tuning to maintain these same power ranges with a larger engine. This is especially true with the 3.8 heads which are the least efficient of all the late engines. This is further crippled by the 3.8 cams, which get a lot more duration at lower lift than the others, but lose this as the lift increases. This was clearly an intentional handicapping of the engine by the factory to keep it further from the GT3 in peak HP output at high speed. When I take one of the 4.0s thats built from a 3.8S engine to a Stage III (Pete is Stage II) I use my R51 heads which are NOT based from a 3.8 head casting, and I also throw away the factory cams.
Now, look at how the 4 liter stomps the pants off it at every RPM range, yet has the exact same curves and peaks. What this means to Pete is he has no need to go past 6,500 RPM; doing so over works the valve springs and puts excess heat in the oil. Not that our springs care, they are designed to dampen our lightweight valves to 9,000 RPM.
The Stock 3.8 file was gathered on the day before Pete's test was done. It was a stock 3.8 that came to us with 16K miles for preventative work to be carried out. It was 100% factory, but very healthy with a fresh tune up and service. It made the same figures we always see from a 3.8 in stock form, and was a mid- pack performer. The most I have had a stock 3.8 dyno at here was 290 HP.
Here's 3 plots to put things into perspective. I never share dyno graphs, because people get too bitchy, so if you get bitchy I'll delete these to and won't post any more, so STFU and learn!
Before you go looking at the stupid freaking, near worthless peak numbers, please note that I have maintained the same RPM range as that of a stock engine while adding over 200ccs to it. This is NOT easy to do as bigger engines tend to inherently move the RPM range down for both Tq and HP.
It takes a lot of time with internal mods to CR, port flow, camshaft timing and tuning to maintain these same power ranges with a larger engine. This is especially true with the 3.8 heads which are the least efficient of all the late engines. This is further crippled by the 3.8 cams, which get a lot more duration at lower lift than the others, but lose this as the lift increases. This was clearly an intentional handicapping of the engine by the factory to keep it further from the GT3 in peak HP output at high speed. When I take one of the 4.0s thats built from a 3.8S engine to a Stage III (Pete is Stage II) I use my R51 heads which are NOT based from a 3.8 head casting, and I also throw away the factory cams.
Now, look at how the 4 liter stomps the pants off it at every RPM range, yet has the exact same curves and peaks. What this means to Pete is he has no need to go past 6,500 RPM; doing so over works the valve springs and puts excess heat in the oil. Not that our springs care, they are designed to dampen our lightweight valves to 9,000 RPM.
The Stock 3.8 file was gathered on the day before Pete's test was done. It was a stock 3.8 that came to us with 16K miles for preventative work to be carried out. It was 100% factory, but very healthy with a fresh tune up and service. It made the same figures we always see from a 3.8 in stock form, and was a mid- pack performer. The most I have had a stock 3.8 dyno at here was 290 HP.
Here's 3 plots to put things into perspective. I never share dyno graphs, because people get too bitchy, so if you get bitchy I'll delete these to and won't post any more, so STFU and learn!
04-24-2015, 08:38 AM
#112
Former Vendor
I told Pete that when he wants a little less manners and 40 more HP that he can send it back :-)
04-24-2015, 09:04 AM
#113
04-24-2015, 09:20 AM
#114
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04-24-2015, 11:17 AM
#117
Very Nice. Thanks for sharing Jake.
To clarify, I wasn't expecting any dyno's. That's the reason why I phrased the question as I did so Jake can point out a few rpm points of his choice that he felt had the most impact from the 4.0 conversion, whether it be below the curve or any peak numbers. Now we know that it has impact everywhere throughout the whole range.
Another good move is to keep power down below and keeps revs down as this is ultimately a street engine and it should last the life of the car and not measured in hours like race cars where their motors only lasts a short while. Pete, it could feel weird shifting at 6500. lol.
I'm not expecting an answer on this one but I'm curious as to know if a stock 3.8 S ecu has the ability to adapt to a 4.0 increase in displacement or if major ecu tuning rework is needed. I know Pete's situation was a bit different as he added on aftermarket bolt ons.
To clarify, I wasn't expecting any dyno's. That's the reason why I phrased the question as I did so Jake can point out a few rpm points of his choice that he felt had the most impact from the 4.0 conversion, whether it be below the curve or any peak numbers. Now we know that it has impact everywhere throughout the whole range.
Another good move is to keep power down below and keeps revs down as this is ultimately a street engine and it should last the life of the car and not measured in hours like race cars where their motors only lasts a short while. Pete, it could feel weird shifting at 6500. lol.
I'm not expecting an answer on this one but I'm curious as to know if a stock 3.8 S ecu has the ability to adapt to a 4.0 increase in displacement or if major ecu tuning rework is needed. I know Pete's situation was a bit different as he added on aftermarket bolt ons.
04-24-2015, 12:39 PM
#118
Former Vendor
I'll say this:
The initial dyno runs for Pete's 4.0 engine with a bone stock ECU were able to yield around 307 RWHP, but the engine was very rich at changeover and above. It had dipped into the high 10:1 AFR values. The ECU is one part of the equation when it comes to DME compatibility. The hardware thats used is the biggest contributor.
We basically picked up 20HP with tuning, but ended up with optimized AFR; which over the long term will be the biggest benefit. Building a 4 liter and keeping a stock ECU IS GOING TO create a rich running condition that will wash down cylinders of oil, increase fuel intrusion and ultimately lead to a compromise.
Pete, Jud is calling you now about shipping.
04-24-2015, 01:42 PM
#120
Former Vendor
I won't let him... Doing that during break in is an almost certain way of extending the break in period.. A long trip on a fresh engine is not part of my break in regimen.
Also, if he picks it up he'd owe Geirgia sales tax which isn't fair to him.
Shipping saves him a lot of money while allowing my break in to occur without compromise.
Also, if he picks it up he'd owe Geirgia sales tax which isn't fair to him.
Shipping saves him a lot of money while allowing my break in to occur without compromise.