Request for feedback on a new engine

[bill308]

Photos of my new engine on the dyno.

[holywood3645]

The numbers Bill... we need the Numbers!!

James

[bill308]

Hi James.

I talked to Peter today and he was still waiting for a replacement timing light. Tomorrow, Peter plans to work out some issues and do final dyno testing on Wednesday, when I will drive out and perhaps pick up the engine. I'm really in no rush for the engine, but at the same time, I don't want to keep spending money on it either. I'm about a year away from putting it in the car and putting the car on the road.

This evening, I sent peter a new, simplified, timing curve for him to play with, if he chooses. Initial advance is 14 degrees up to 1200 rpm, then to 32 degrees between 3500-8000, then to 20 degrees at 9500 and beyond. This curve is designed to be easily changeable.

Bill

[Certified Lotus]

Congrats Bill ! Must be great to see and hear your new engine running. I'm still waiting for final assembly on mine and the dyno runs. I'm a bit jealous

[pharriso]

I plan to dive out for the next tuning session on Tuesday, 5/5/15.

Wish me luck,
Bill

You plan on swimming Long Island Sound?

[bill308]

Thanks Glen. I'm sure your engine will be up and running soon too.

Good one Phil. My typing and swimming are not what they once were. How far from Port Jefferson are you? Did you contact TTR about shipping your gearbox?

Today there was good news and there was bad news. The bad news is that they were working on my engine going into this evening. The good news is Peter found the trigger wheel was improperly indexed on the crank. Correct alignment necessitates that the center of the sensor must be aligned with the trailing edge of the 11th tooth after the two missing teeth when the engine is at TDC #1. That is, the sensor is placed counterclockwise from the missing teeth. The engine rotates clockwise, when viewed from the front. My understanding is the trigger wheel was mounted clockwise 11-teeth from the missing teeth reference. Peter swapped around the spark plug wires to somewhat compensate Monday, when we first started it. I'm surprised it started at all, but it did. As the timing lights were inoperative, we had no way to measure where the timing really was. Peter is addressing this issue as we speak. There is still a possibility the engine will be ready tomorrow, but I need to call Peter in about an hour to see where we are.

Bill

[pharriso]

How far from Port Jefferson are you? Did you contact TTR about shipping your gearbox?

Bill

We're about 30 miles west of Port Jeff. I did not bother contacting TTR, did not make sense if my load was not consolidated with yours. I am using TransGlobalExpress to ship the Gearbox & clutch assembly, 150 pounds door to door including insurance, not too bad.

[bill308]

Sounds like you got a good deal Phil. 150 GBP, door-to-door is hard to beat.

Well, I didn't make it out to see the engine builder today, but I will tomorrow.

So, I talked to Peter and the engine is playing pretty good. The timing is reasonably sorted, but perhaps not yet optimized. If I understood correctly, Peter said 191 bhp and 167 lb-ft torque. Tomorrow, we'll tweak it a bit more and see if we can get 200 bhp. Mainly, we'll increase timing from 32 to 34 degree BTDC. Carburation is pretty good at this time and Peter said he bored out the 36 mm chokes to 38 mm. This resulted in a bit more top end and no noticeable low end loss.

Bill

[bill308]

We played with the engine timing yesterday and found 32 (engine) degrees total BTDC, to be the best setting on 93 octane, (MON+RON)/2, pump gas (max 10% ethanol). The highest dyno pulls showed about 193 bhp and 165 lb-ft, just a bit than what Peter saw Monday. When Peter makes copies of the dyno sheets, I'll (plot)/post them.

Under load, the engine would stumble when slamming the throttles open at 1500 rpm. But from about 2000-2500 rpm and under load, the throttles could be slammed open with only a modest hesitation. I believe low speed response can still be improved with more precise balancing (4-tube manometer in lieu of an SK Synchrometer). There was no indication of knock or pinging at any time. I'm wondering how it will run on 91 octane or lesser grade of gas?

A DBE 114 and 104 cam were fitted. According to DBE catalog, the 114 cam (Exhaust) has 0.413 inches gross cam lift and a duration of 243 degrees at 0.050 lift. The 104 cam (Intake) has 0.440 inches gross cam lift and a duration of 259 degrees at 0.050 lift.

The engine is now safely home and will be stored with a bit of Marvel Mystery Oil in the bores, until fitment in my 26r clone. In the end, Peter thinks we could have gone with a bit more cam to get bigger numbers, but I reminded him that this was supposed to be a street friendly driver from the start. I think I got what I set out to build. I'm a happy camper.

Rohan was very good with his early prediction of 190 bhp. Good job all around.

Bill

[bill308]

A couple of other details of note while I'm waiting for copies of the dyno sheets.

The all steel bottom end should be good to 9 krpm+
The valve hardware should also be good to 9 krpm+
We tested the engine to 7.5 krpm
The ignition curve falls off after 8 krpm, to serve as a soft rev limiter
The dyno shows at least 180 bhp from 6-7.5 krpm
The engine is considered fully broken in
We actually started full throttle dyno pulls after about 10-minutes of running and put perhaps an hour's worth of running on the engine.

Today I put the engine on a roll around engine stand and purchased some Marvel Mystery oil to coat the bores and act as a rust preventative. It will be about a year until It will be fired up again in the 26r clone I'm building.

Bill

[seniorchristo]

Hi Bill
Did you ever consider a 4 valve BDA type head for your project? If so, what were the considerations, pros and cons? I am considering a similar 26R type project using a BDT small port head. Other than the WOW factor I'm not sure there would be any advantages. Maybe just a cost disadvantage. My goal would be 180+ HP at 7500-8000 rpm and extremely streetable. I'm still hoping to visit you at some point. Thanks for the interesting thread!
Chris

[bill308]

Hi Chris.

Years ago, I did consider a BDA. I had a conversation with Dave Bean about this and he recommended a twink head. He said you could get almost as much reliable bhp from a twin as a BDA, only a lot cheaper. David Vizard, in his latest book on porting and IIRC, wrote a good 2-valve may be superior to a 4-valve for street use. I don't recall the reasoning at this point, but he did make a reasonable argument. David is a degreed engineer, author, and has done extensive flow and dynamometer work to validate his methods. The other thing is many BD engines are based upon a tall block. Clearance to the bonnet is desirable.

Initially, I was thinking a twink with an overbore and xflow crank. Later, that morphed into an alloy block with an 89 mm bore and a steel bottom end with xflow stroke, so 1930 cc's. The goal was a well behaved 180 bhp on pump gas. I got 193 bhp and a useful rpm range up to 7.5 krpm and a true red line of 9k, valve train limit.

With regard to the BDT, make sure it fits. Would this be a turbo model?

Please stop by for a visit if you get a chance.

Bill

[seniorchristo]

Bill
My HP goals are similar to yours, 180 -200. The Cosworth BDT cylinder head was designed for a turbo engine. I'm being told it will work well for the street because of its small port design and its capability of being built to lower compression ratios. I am having conversations with Rita at Richard Wilcox trying to determine if this is a feasible project. She is telling me all BDT engines were built with aluminum "thick wall" blocks with minimum bore size of 85.4 mm and they are very difficult to obtain. I'm not sure why some of the current aluminum blocks being offered today won't work or even a sleeved LTC block but Wilcox seems to be the knowledgeable source for BDA related information. The person selling the cylinder head (Kim Baker ex Corvette racer) tells me a 16 valve head is more tractable than an 8 valve head. Who to believe? I am trying to learn as much about these engines as possible. Are there any books or publications that are useful in this regard?
Later,
Chris

[rgh0]

Compared to a 2 valve head a 4 valve head can generally be more tractable at similar HP on the same bottom end as it can develop the same HP at more conservative valve timing due to better breathing.

However there are many variables involved such as valve lift, actual valve and port sizes and shapes possible with the 2 valve versus 4 valve head and combustion chamber shape so it is not a definite get a BD head because it will be better. The modern high lift short duration cam shafts appear to have also made 2 valve twin cam heads much more competitive in road engines compared to a BD head in terms of drive ability at a specific HP

A good general guide on cam shaft selection for 2 and 4 valve engines is
"How to choose camshafts and time them for maximum power" by Des Hammill

cheers
Rohan

[bill308]

Thanks Rohan.

Initially, I considered my existing head. I put a lot of time into setting it up per David Vizards book on porting the twin cam head. I even did the radiused valve seats that seemed to work very well with Sprint Cams. But the new engine needed to support the area near 180 bhp with a wide torque band. So what to do?

I went with a Stowe head and relatively hot, but not optimum, fast street cams, recommended by DBE for my application and a valve set consisting of race length, D-production size valves, and a special spring pack from Marcovicci-Wenz Engineering, good for a reported 9k rpm. Most importantly, I bumped up displacement to 1.93 liters, for good torque.

I have to reread Vizards book, "Port & Fow Test", to find the passage where he discusses 4 vs. 2-valve characteristics. IIRC, one of the issues was relatively poor air/fuel mixing in a compact 4-valve chamber. Also 4-valves tend to pass trough a little fuel air mixture on overlap, limiting mpg. I don't know if these are relevant arguments on the BD series heads, for srteet use.

Bill