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Taking a Stock Engine with Stock Turbo to the limit....
- Thread starter murphster
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forcefed3.8's
Buckeye Bullet
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Murph or you????
I am thinking about putting a stock engine in my car with my existing TH400 and 12 bolt 3.31 gears and see what it will do. I need to change it up.
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both cars I setup with similar mods he has a couple more items for weight reduction
both have th400rmvb ptc 9.5 18blade 3.23 spool MT275/60 pro,trz sway bar strange dbl adjust rears baseline relocate uppers . both cars went with a walbro 255lph inline with a cell
both have th400rmvb ptc 9.5 18blade 3.23 spool MT275/60 pro,trz sway bar strange dbl adjust rears baseline relocate uppers . both cars went with a walbro 255lph inline with a cell
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That would be very cool, plus you have a tighter converter I believe. You have the template lol. I don't think I there is lack of data posted on what to do....
So I looked over more of my logs and timeslips from the spring.... looks like I gained 2 mph and 2 tenths in the 1/4 from my first passes. I ran 115mph on the first pass at a little less boost and in cooler weather. Adding a little timing and leaning it out a hair seems to have gained a tenth and a mph. And the pre-turbo nozzle and cold air setup may have gained another tenth and mph. Individually they are all small gains but they all add up, especially on the top end.
forcefed3.8's
Buckeye Bullet
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I have an 18 blade. I was thinking a 16 or even a 15 blade would be the ticket for stock cam and turbo.
I agree. Just couldn't justify spending the $ on another converter as it would be more money than I have in the stock engine and turbo swap combined.
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A quick mass/heat balance shows you should be getting about 30 degree f drop with a pre turbo M5 at an alky 129 psid. Used specific heat of air at constant pressure. Not sure if that is best, but process is neither constant pressure or constant volume.
Looking at my logs compared to my last run without the pre turbo nozzle and cold air setup.... I was reading 40 degree colder air coming out of the turbo while pre staging before the alky was even on. This stayed constant throughout the whole run. Backpressure was the same.
This tells me that the better air prob had more to do with it than anything. I wish I had an extra temp sensor on the MAF pipe that would tell more. The cold air coming from the headlight opening wouldn't show up pre staging so it probably didn't make the difference. The sun was down too so that prob minimized the cold air setup vs a hot sunny day with heat pouring off the track surface but colder air in equals colder air out so it can't hurt.
Its all trial and error with these different things. Going faster so must be doing something right though...
This tells me that the better air prob had more to do with it than anything. I wish I had an extra temp sensor on the MAF pipe that would tell more. The cold air coming from the headlight opening wouldn't show up pre staging so it probably didn't make the difference. The sun was down too so that prob minimized the cold air setup vs a hot sunny day with heat pouring off the track surface but colder air in equals colder air out so it can't hurt.
Its all trial and error with these different things. Going faster so must be doing something right though...
Just wanted to show a log of one of the runs I made last Friday. I added boost up top from this run and it gained maybe 0.5mph. A small but noticeable gain. Adding boost down low seemed to hurt the 60ft with the extra backpressure and my best runs were only adding boost after 1st gear.
This was the 5th run, 11.25@118.3 mph with a 1.53 60ft. Only averaged around 21.5psi boost on this run.
Few things from the log:
- only 1 psi drop from turbo to plenum, 22.5psi to 21.5psi
- rpm finished at 4850
- backpressure ratio was 2.13:1
- inlet temp of 70 degrees after the alky
- EGTs showed a drop from 300 to 100 degrees through the intercooler
- injector duty cycle was only 47.8% of my 42lb injectors. Lots of alky being injected.
Another log with about 2 more psi after 1st gear was about 45 degrees hotter after the turbo at 345 and dropped to 115 after the intercooler. Backpressure ratio went up to 2.32:1. I did gain a little less than half a mph though even with the extra backpressure and hotter air. I tried adding timing one run down low and it had no effect.
This was the 5th run, 11.25@118.3 mph with a 1.53 60ft. Only averaged around 21.5psi boost on this run.
Few things from the log:
- only 1 psi drop from turbo to plenum, 22.5psi to 21.5psi
- rpm finished at 4850
- backpressure ratio was 2.13:1
- inlet temp of 70 degrees after the alky
- EGTs showed a drop from 300 to 100 degrees through the intercooler
- injector duty cycle was only 47.8% of my 42lb injectors. Lots of alky being injected.
Another log with about 2 more psi after 1st gear was about 45 degrees hotter after the turbo at 345 and dropped to 115 after the intercooler. Backpressure ratio went up to 2.32:1. I did gain a little less than half a mph though even with the extra backpressure and hotter air. I tried adding timing one run down low and it had no effect.
Looking at whether the pre turbo nozzle makes a difference.... I compared some logs running similar boost. Weather wasn't too much different either but maybe a little cooler out now then the run without the ore turbo nozzle. Runs show a difference of 54 degrees at turbo outlet at end of the pass, 304 vs 360...
I think the alky vaporizes in the turbo as the ambient air is compressed and heated a few hundred degrees.
Blow-through/draw-through turbos have been around a while and were factory setups in the 70s. A lot less boost but all the fuel was put in pre turbo. People have run these setups with higher boost with no issues and you figure all the fuel put in must be a lot more volume than my M5 nozzle is putting out....
When I upgrade to an M10 or M15 nozzle pre turbo then we'll see lol
Blow-through/draw-through turbos have been around a while and were factory setups in the 70s. A lot less boost but all the fuel was put in pre turbo. People have run these setups with higher boost with no issues and you figure all the fuel put in must be a lot more volume than my M5 nozzle is putting out....
When I upgrade to an M10 or M15 nozzle pre turbo then we'll see lol
Another thing I've looked at to reduce backpressure is headers and downpipe/wastegate. Equal length headers are supposed to be superior for turbo efficiency over log style headers because it reduces turbulence from the various pulses. Maybe a Kenne Bell/ATR style header with a collector near the turbo would be a better design. Another thing is a smooth transition coming off the turbine to the downpipe rather than opening to a big step. A downpipe with no wastegate provision may be the best solution. Also, for an external wastegate setup, it will be better for turbo efficiency to dump to atmosphere rather than reintroduce the air back into the downpipe.
It may be very small gains, if any, for these but it may be worth a try. I may have access to all of these to try them except that the downpipe is only 3" vs my current 3.5". It may not matter, but if its only a miniscule loss going to the 3" it may wipe out any gains.
It may be very small gains, if any, for these but it may be worth a try. I may have access to all of these to try them except that the downpipe is only 3" vs my current 3.5". It may not matter, but if its only a miniscule loss going to the 3" it may wipe out any gains.
Went to Atco for Black Friday. No real changes except for a higher quality trans cooler with a fan and upgraded lines. The rental was pretty rough on the trans with all the passes and this should help. Atco was a sh** show with all the cars there and how slow they were pulling lanes, cleanups, etc. Just ridiculous.
I didn't set a new best time but set a new best mph.. 11.22@118.89. If I could have hit it harder on another pass might have made it into the 11 teens. Weather was crisp, around -600 DA.
Got a good in car video too:
left lane:
I didn't set a new best time but set a new best mph.. 11.22@118.89. If I could have hit it harder on another pass might have made it into the 11 teens. Weather was crisp, around -600 DA.
Got a good in car video too:
left lane:
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