Sent: Thursday, November 09, 2006 8:13 PM
To: djmds@shaw.ca
Subject: TBI injection
Hello Dave,You purchased some TBI conversion parts from me awhile back and I'm curious about how your project is going. Care to share some details?
thanks,
Rick
http://sidedrafttbi.com
> From: David Murray [mailto:djmds@shaw.ca]
> Sent: Friday, November 10, 2006 8:55 AM
> To: rick@sidedrafttbi.com
Subject: RE: TBI injection
Amazing, I was just thinking this morning that I should let both you and Aaron know how things worked out.
My engine mods were more traditional: new cam (Goodparts GP2), 1.65:1 rollers (also Goodparts), 10:1 compression, ported head, exhaust header, lightened flywheel, and electric fan. I also added a Toyota 5-speed, a great upgrade to the stock 4-speed with no OD. The HP gains were a little more than I expected; I was looking for between 100 and 110. The car is definitely much more fun than before.
The system went into the car with no problems (well just a couple of very minor ones) and was tuned fairly quickly. One of the biggest problems I had was slow speed drivability where the car would surge very noticeably. I had the dizzy re-bushed, a new extension shaft fabricated without the welded-on advance lock (the advance mechanism had all been removed) and a bearing inserted into the top plate where the extension shaft passes through. This eliminated all the wobble and play associated with the dizzy and greatly improved the drivability at low speeds but did not fully correct the problem.
I finally tracked down the last culprit just before the weather turned bad. John had originally indicated the TPS should be adjusted to provide 0.5V output at idle - this resulted in a scaled TPS reading of -3.6%. I readjusted the TPS to 0.54V which gives a scaled TPS reading of 0% and my slow speed problems disappeared. I believe the low TPS setting was confusing the ECM's transition into and out of idle.
Once I got the slow speed issue resolved I had a chance to get the car on the dyno and do some WOT tuning. Again here I was a little confused as to the correct procedure - John patiently explained it to me until it finally sunk in.
One last issue to resolve; a large downward oscillation in the HP curve between 4600 - 4900 rpm. Ignition changes impacted the result so concentration was centered on the ignition system. After a day of head scratching, making changes, and no progress one of the other guys in the shop walked by during a pull and asked why the back of the car was bouncing so much. It turned out the car pulled smoothly until 4600 rpm when the back of the car bucked until the engine passed 4900 rpm (~70mph in 3rd) resulting in poor power transfer to the dyno drum. I haven't had a chance to pursue this issue any further yet but wouldn't be surprised if it was just the tires - the PO installed the cheapest tires he could find before selling the car and I haven't changed them yet.
End result:
My mechanic also lets everyone who comes into the shop know about the conversion and has several possible customers - several have asked about other applications, i.e. TR3, TR4, Morgan +8.
- - 125 HP (rear wheels) could likely get another 5 - 10 hp but would rather be on the safe side
- - 130 Ft lb torque
- - increase of ~4 mpg from before the engine rebuild (initial 60Hp and 70 ft lb torque)
- - car starts on 1/2 crank even at -10C
- - generated quite a bit of interest at the one show I made.
I was fortunate in that my Dyno is located in a British car shop – though they do dyno work for others (www.sportscarparts.ca). My main competition was other 6's, MGB's, Jag's, a couple of Morgans, and a TVR. They did snicker a little at the before results as they build a lot of vintage race car engines. The before state of the car/engine also was less than ideal, hence the lower than stock numbers.
I have no problems in discussing with anyone my experience with the TBI setup and I know my mechanic would be interested in your supercharger setup. He was most impressed with the quality of the parts you supplied.
David Murray
Calgary, AB, Canada
djmds@shaw.ca
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