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Learning how to build Lotus Seven replicas...together!
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PostPosted: August 5, 2019, 9:16 pm 
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Location: Carlsbad, California, USA
The car looks like it drives very smoothly in the video. I do see what you mean about it bogging down a little below 3000 RPM.

Was there a significant weight difference between the current engine and the one you took out? Did you have to change other things (springs, shocks, rollbar) due to the engine change?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: August 5, 2019, 10:11 pm 
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Hi Lonnie,
The net was a reduction of 50 lbs. The T5 is 20 lbs lighter than the Miata 6-spd, so the other 30 lbs came from the power unit. I don't have enough time on this setup yet to know if the handling will dictate any suspension changes, but it didn't do anything spooky. I only made two runs and then loaded it on the trailer so that I could take my time to study the data logs at home.

Ron


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PostPosted: August 6, 2019, 12:11 pm 
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It's really cool to see all that data displayed in the video, Ron. I'm so far from that stage that I won't ask any questions of you. It would be "in one ear and out the other" right now.

Several years ago I purchased a suspension design package that (with an optional module) will allow you to study the track data in sync with suspension sensors. My long term plan is to teach myself chassis dynamics using my Locost as the real-life lab device. Like I said, I'm a ways off from that, so there's no point in spending a lot of time on it. However, it's why I've gone the extra mile to make all my suspension parts adjustable or easily replaceable in the future.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: August 22, 2019, 8:39 am 
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Nice work Ron, that was one quick conversion!!! I need to go on a Seven Saturday schedule!! :D

I’ve been studying your pictures as I know that I will have to change my engine eventually to something more powerful.

If I’m reading right you’re using the Tec-S as a Stand Alone ECU for the engine, unlike some conversion who uses the GM ECU? From the pictures I’m seeing a trigger wheel so I guess you’re using the electromotive ignition as well? Do you feel this is the proper way or less complicated way?

I also think I saw a throttle cable? Did you swap the fly by wire throttle body for a mechanical throttle body ? which one did you use ?

How powerful do you think your current package is ? Where do you think you can take this vs the Duratec ?

Sorry for the 101 questions, but you open the can by posting your pictures  :D

Again I have to say Great work !!!

Thanks


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PostPosted: August 23, 2019, 4:58 pm 
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Hi Jawfish,
Yes, I'm using the TEC-S for injection and ignition. Yes, it's less complicated. It remains to be seen if it's "proper". Specifically, using a basic ECU doesn't allow for the VVT cam control. But, in my study of the load/rpm tables being used by the mfgr's, the path through the tables (intake and exhaust) for WOT just uses one setting for each cam. The timing variations used for mileage and emissions occurs in the other areas of the tables. So, I degreed the cams, determined where I wanted each cam to be, within it's range of adjustment, and made locking blocks to defeat the VVT. I then had to position the cams where I wanted them without using the factory alignment slots and tool. I don't have enough data yet to report performance numbers because the acceleration enrichment was way too fat on the first outing. I expect that I'll be experimenting with the intake cam position to try different amounts of overlap. So, stay tuned for updates on this.
Yes, it has a throttle cable which is a combination of mechanical linkage from the gas pedal to a drum and then a cable from the drum to the throttle body. See pics. The throttle body is from a mid 90's Nissan 300ZX turbo. A slight kiss with the rat-tail file on the TB mounting holes and it bolts onto the stock manifold.
No need to worry about asking questions on this site.

Ron


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PostPosted: August 23, 2019, 5:20 pm 
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seven13bt wrote:
it has a throttle cable which is a combination of mechanical linkage from the gas pedal to a drum and then a cable from the drum to the throttle body

I love it! That's my kind of thinking, great pics of the set up :cheers:

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Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
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PostPosted: August 24, 2019, 7:48 am 
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Thanks Ron !!!
Brilliant. I was actually thinking that an analog throttle body was the way to go. I think the stand alone is fantastic as your not dependant on getting a manual ECU and should be less problematic, but it is a more expenselive option.

I noticed a welded exhaust manifold, did you just reroute the turbo or you went with a different turbo.

I noticed an external oil pump did you go dry sump ? Are you using the original oil pump ? I only noticed 1 line ?

I really appreciate seeing this and your answers, its really restarting the little gears in my mind. I'm taking my car out of staorage and bringing it to the new garage to finally finish it this winter.

Cheers
Fred


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PostPosted: August 24, 2019, 9:49 am 
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Fred,
I made the exhaust manifold to locate the GT-2056 turbo where I wanted it.
The external dry sump pump is just for the scavenging. The stock pump pickup passage is in the front cover and cast into the "front" of the stock pan. I used a block of billet aluminum to provide the supply routing from the dry sump tank to the stock opening in the front cover.


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PostPosted: August 29, 2019, 6:42 am 
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Very nice Ron. Love it.

I missed working on race cars to make those little things and some bigger.

Keep us posted on how tge car performs and all the things you're doing to it. I can't get enough and I'm sure I'm not the only one.

Cheers
Fred


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PostPosted: September 8, 2019, 11:22 am 
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Made some adjustments to the tune and ran it at the autoX yesterday morning. It ran much better, but the acceleration enrichment is still too much. Since I still didn't have any load data up to redline (6500), I reviewed the morning data and reduced the acceleration parameters so that I could make some redline passes after the event.
Results: 20 psi boost by 4200 rpm (no creep to 6500), 154 ft-lb whl torque at 4500 rpm and 166 whl hp at 6200 rpm. Enrichment was better, but it still needs more reduction.

Last run in the morning:

https://youtu.be/EW3CMPwtZX4


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PostPosted: September 11, 2019, 11:58 am 
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Cool run. Looks fast. But, what's that whistling sound when you back off the accelerator?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: September 11, 2019, 12:33 pm 
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Lonnie,
That's the pressurized air being released by the blowoff valve when the throttle closes. It's the red contraption at the back of the engine in the July 27th pics. It's mounted in the plumbing between the intercooler and the throttle body.


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PostPosted: September 12, 2019, 2:37 pm 
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OK, thanks, Ron. Your engine sure seems to be well behaved. It looks like almost linear in terms of power output. I've had two turbocharged cars. They both had that "hesitant" characteristic. You floor the throttle, but have to wait for the turbo to kick in. It looks like turbo technology has come a long way since then.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: September 12, 2019, 6:03 pm 
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Lonnie,
Yes, turbo materials and manufacturing have made big improvements from a couple of decades ago. However, one can still put on a turbo that's too large and you'll get a big kick at the top end but nothing coming out of a corner. With the small turbo I'm using, getting on the gas exiting a corner at 3,000 rpm will start building boost immediately and be near full boost in less than 1,000 rpm and stays there up to 6,500. The boost vs rpm and torque vs rpm curves look the same. The hp vs rpm climbs all the way up to near redline. :cheers:

Ron


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