BDR How do I know what my max rpm is? Ans: Dyno says 7,400

[anthony1956]

All the pics I can find: (Higher res available if helpful.)

Edited September 4 by anthonym
add pic I missed 1536

[anthony1956]

I never noticed this before: 

[OldAndrewE]

OK, my thoughts Anthony - others may have different thoughts.  I think they are standard rods that have been worked on, presumably to balance, whether they have had any other treatment I cannot say.  The rod bolts are after market, probably ARP as you said.  The mains caps are certainly not standard 711M.  The crank looks standard but with a lot of balancing work

[anthony1956]

That interesting, more than I have ever known. Forgive my ignorance what are "main caps"?

How can you tell they have been worked on? Likewise the crank?

Can you see anything about the pistons? I am thinking they are Forged. This is because Geoff said to me when I bought the car that "the pistons are xxxxxxx", which I misremembered as steel which you corrected. It seems all that is left for those days is forged. Not that it makes any difference to anything, but not knowing how he had the engine built by Cosworth has always been a bit frustrating.

I am wondering what general instructions to Cosworth might have resulted in this work - "blue printing"? The Dellorto carbs in themselves suggest a desire for more performance control and the much bigger than standard main jets indicate a desire for performance at the expense of "round town". Being an aircraft engineer I have always presumed he knew what he was doing and what he wanted, which is why I don't want to change what he built, just to make the most of it. Certainly when I got it, it looked a million dollars and  turned out to be well hammered, shall we say, so we soon fixed that, now 20 years ago. 😉 

Edited September 4 by anthonym

[Guy Lowe]

21 minutes ago, anthonym said:

Forgive my ignorance what are "main caps"?

They are the crankshaft main bearing caps 

 

[anthony1956]

ahhh, the parts that hold the crank in place presumably with bearings of some sort within

thanks 

[anthony1956]

do they look like billet steel main caps? their square chunkiness is making me wonder, and from what I am reading because of non standard caps the bores would have (had to be) line bored so as to line them up properly - as in Cosworth Engineering would do that as part of the caps replacement process.

Edited September 4 by anthonym

[anthony1956]

morning Andrew 🙂

[OldAndrewE]

9 hours ago, anthonym said:

do they look like billet steel main caps? their square chunkiness is making me wonder, and from what I am reading because of non standard caps the bores would have (had to be) line bored so as to line them up properly - as in Cosworth Engineering would do that as part of the caps replacement process.

Yes, these are the standard caps on my 711M engine

[anthony1956]

oh I see, all rounded and maybe a bit smaller, makes mine look more like they have been fashioned out of a block of metal; "billeted" is it?

Here's my speculation about my engine, based largely on your thoughts:

https://www.caterhamlotus7.club/blogs/entry/1109-bdr-so-what-specification-is-my-engine-it-was-bought-direct-with-special-spec-but-what/

and I'm guessing these different depth holes are evidence of the crank being balanced:

Edited September 5 by anthonym

[OldAndrewE]

1 minute ago, anthonym said:

oh I see, all rounded and maybe a bit smaller, makes mine look more like they have been fashioned out of a block of metal; "billeted" is it?

Exactly.  Regarding the rods the main 'shank' of your rods are all polished smooth, presumably as part of the balancing process.  Standard rods would have the 'as forged' finish all over.  There are various drillings and grindings on the crank which again are part of the balancing process.  I cannot tell anything about the pistons.

[anthony1956]

yes from what I have been reading when making the modifications to an engine like this it seems not using forged pistons would be rather odd and that aligns with Geoff's comment (crucial detail forgotten) to me about the pistons it has - there seems only to be the binary choice of normal or forged; well, or "custom", but I doubt this. So lots of buyer specified work, none of which attempting to increase its BHP, but smoother power delivery, throttle response, longevity, drivability and fuel efficiency; I suppose the sort of things an aircraft engineer would be aware of. And of course capable of higher rpm, not that there would be much point in going there if the peak is at 6250 - I have a rolling road report somewhere, I'll have another look with renewed interest. 

Edited September 5 by anthonym

[anthony1956]

has anyone got underside pics of their cast pistons?

I've been googling and come up with a list of possibilities to identify forged pistons, but have no idea what cast ones look like esp from underneath, here's my list from my notes:

1. Thicker Construction

• Forged pistons typically have thicker walls and skirts compared to cast pistons.
  This is because the forging process creates denser and stronger material, which allows the piston to withstand more stress, particularly in high-performance applications. From underneath, you might notice that the piston looks more solid and robust.

2. Smooth and Consistent Surface

• The underside of a forged piston often appears smoother and more uniform compared to a cast piston.
  Cast pistons may have a rougher texture on the surface due to the casting process. In contrast, the forging process typically leaves a smoother surface finish.

3. Visible Forging Marks

• Forged pistons can sometimes show evidence of the forging process, such as seams (where the dies met) that are typically smoother and less pronounced than those on a cast piston.
  Some forged pistons may have specific indentations or marks left from the forging dies, which can be a giveaway.

4. Reinforced Pin Bosses

• The gudgeon bosses (the areas where the gudgeon goes through) in forged pistons are usually much more reinforced and thicker than in cast pistons.
  From underneath, you might notice that the area around the pin bosses is bulkier and more substantial, a common feature of forged pistons designed to handle high loads.

5. Lack of Casting Flaws

• Unlike cast pistons, forged pistons typically don’t show casting imperfections such as small bubbles or irregularities.
  When viewed from underneath, forged pistons will appear more uniform and free of casting defects like seams or irregular pockets.

6. Minimalist Design

• Forged pistons are often designed with less excess material than cast pistons. This results in a more purposeful and streamlined shape, with less material in non-critical areas. While still strong, they may appear lighter and more efficient in design when viewed from underneath the engine.

7. Manufacturer Marks (fat chance!)

• High-performance forged pistons are usually marked with branding or part numbers by the manufacturer. These marks may include the company name (e.g., Mahle, JE Pistons, Wiseco, etc.) and can sometimes be visible on the underside of the piston. If you can see any identifying marks or numbers, these could point to a specific forged piston manufacturer.

In short:

• Thicker, robust design - this needs someone well familiar with both
• Smoother surface finish
• Reinforced gudgeon pin bosses - this one carries my hopes of being able to see and compare
• Minimal or absent casting flaws
• Manufacturer stamps or marks - not seen any

One of my gudgeons and bosses, need a cast one to compare:

and off the skirt of a piston, 

 

Edited September 5 by anthonym

[anthony1956]

2 hours ago, OldAndrewE said:

Regarding the rods the main 'shank' of your rods are all polished smooth, presumably as part of the balancing process.  Standard rods would have the 'as forged' finish all over

I guess/hope this illustrates: shiny bits and rough bits

[OldAndrewE]

54 minutes ago, anthonym said:

I guess/hope this illustrates: shiny bits and rough bits

[anthony1956]

Good that’s what I was hoping 

that’s an awful lot of duraglit to do that

Edited September 5 by anthonym

[anthony1956]

@OldAndrewE1985 S3 1700 XFlow.  Undergoing full restoration

That must be very similar to my BDR restoration completed last year. All sorts of questions spring to mind.

Edited September 5 by anthonym

[Gridgway]

5 hours ago, anthonym said:

yes from what I have been reading when making the modifications to an engine like this it seems not using forged pistons would be rather odd and that aligns with Geoff's comment (crucial detail forgotten) to me about the pistons it has - there seems only to be the binary choice of normal or forged; well, or "custom", but I doubt this. So lots of buyer specified work, none of which attempting to increase its BHP, but smoother power delivery, throttle response, longevity, drivability and fuel efficiency; I suppose the sort of things an aircraft engineer would be aware of. And of course capable of higher rpm, not that there would be much point in going there if the peak is at 6250 - I have a rolling road report somewhere, I'll have another look with renewed interest. 

I don't think I see it really like that.  The routes to getting more out of a BD engine pretty much have one thing in common - higher revs.  You build it to carry on higher up the rev range and function there.  More porting and potentially bigger valves - more gas in and out (esp at higher revs).  Forged pistons - stronger at higher revs and can work at higher compression.  Steel crank and rods - stronger to handle higher revs.  More detailed balancing - higher revs. And so on.  Lighter steel flywheel - higher revs.

Now there are other side effects such as better throttle response with a lighter flywheel.  But things like longevity, drivability, fuel efficiency (hehehe) are not normally high priorities of someone building a higher spec BD.

Not sure how that helps your quest (mainly because I'm not sure what your quest is), but might be a helpful perspective.

Graham

PS what are you thinking of doing with a gas analyser?  Mapping is normally only concerned with AFR and uses a lambda or wide band lambda for that.

[anthony1956]

Hi Graham, interesting nevertheless. If I read your text correctly it is from the "more power" (faster car) point of view? As in "to get more out of a BD engine" means to desire it to go faster by having more brake horsepower (or whatever measure). ?

[anthony1956]

35 minutes ago, Gridgway said:

PS what are you thinking of doing with a gas analyser?  Mapping is normally only concerned with AFR and uses a lambda or wide band lambda for that.

SORRY MISSED THAT, I use my gas analyser all the time to prepare my cars for the Swiss "m.o.t." . This avoids an hour's driving and 50 francs a time for each test (by a local garage not the test centre). So since I have it already I am exploring using it to check the usual emissions above the usual range, ie. 3 to 7k rpm. While carb cars have existed for many many years without checking this and still do, it seems there is a body of thought that thinks I should check these ranges and since i have the kit to do that, why not? Just a bit of fun really. There's no 02 sensor on my BDR , my K has a wide band lamda set up by the two steves.

It always surprises me owners don't take much or any interest in their engine efficiency even doing all sorts to avoid knowing. It's so easy to do. Granted the kit is mega bucks so group ownership would be better - but iirc I checked and there's no interest in doing that. So. Horses for courses. 

[anthony1956]

46 minutes ago, Gridgway said:

I'm not sure what your quest is

Reconstructing what my car's builder, Geoff Mansell, had in mind and what specification he ordered for the engine from Cosworth. 
My current estimation is here: https://www.caterhamlotus7.club/blogs/entry/1109-bdr-so-what-specification-is-my-engine-updated-speculated-specification/

 

[Miker7]

The pistons in the BDA need (i think) 4 machined cut outs for the valves. The block is a xflow block. Did ford ever do a BDA piston? Can you buy a cast BDA piston? I'd imagine that any pistons available for a BDA are forged and not cast due to the performance nature of the engine and lack of mainstream manufacture. I've no way of proving this, except if you google pistons today I can only find forged.

[Gridgway]

38 minutes ago, Miker7 said:

The pistons in the BDA need (i think) 4 machined cut outs for the valves. The block is a xflow block. Did ford ever do a BDA piston? Can you buy a cast BDA piston? I'd imagine that any pistons available for a BDA are forged and not cast due to the performance nature of the engine and lack of mainstream manufacture. I've no way of proving this, except if you google pistons today I can only find forged.

From my BDR build sheet it mentions the use of AE Hepolite pistons which I would be tempted to think are cast not forged, but that's just a guess.  I can't find a reference to a Hepolite piston for a BD if I google though.

[Gridgway]

58 minutes ago, anthonym said:

Hi Graham, interesting nevertheless. If I read your text correctly it is from the "more power" (faster car) point of view? As in "to get more out of a BD engine" means to desire it to go faster by having more brake horsepower (or whatever measure). ?

Yes my assertion is that the likely reason for an engine builder to do those things is to get a higher power engine which almost always (if not always) involves higher RPM.

I run my BDG up to 9,500 (in racing) although I am told they used to use more rpm back in the day.

[anthony1956]

1 hour ago, Gridgway said:

run my BDG up to 9,500 (in racing)

wow! bet that sounds quite something. 

1 hour ago, Gridgway said:

Yes my assertion is that the likely reason for an engine builder to do those things is to get a higher power engine which almost always (if not always) involves higher RPM.

Yes I quite agree. However, it wasn't the engine builder who specified the work, it was the customer Geoff Mansell (aircraft engineer), so the motive was Geoff's not Cosworth Engineering's. He was very specific when talking to me about how he wanted the engine modified to his own spec which was why he bought it direct from Cosworth. So far nothing we can see has been of a sort to generate more power and on the rolling road (shhh) in about 2002 she showed up as 169BHP (I'm searching for the RR curves report),  bog standard. However, everything about her was shall we say "weary". For example worn out stub axles and on and on - at I think it was 33,000 miles, but the engine seems perfectly happy, not surprising given all his mods that contribute to longevity amongst other things, and being able to rev to 7,000 would (does!!) make it easier to stay on the cam if the power is at 6,250; he used a five-speed box iirc.

Just trying to get inside his head to see what he wanted to achieve. More power would not seem to be an objective. Maybe he did hill climbs in a class - he lived not far from the one near Tewkesbury.. (it will come to me)...

Me? I've installed 4:1 open diff and sixspeed. 😉

any videos of you racing? Always love that sort of thing.. 

Edited September 5 by anthonym