428 replies to this topic

[CHILL Gone DUTCH]

Exmantaa's mate speedster4fun's car. He does not post much.   They are both working on their timing atm (though exmantaa uses a 2.0 lsj, and speedster4fun uses the B207)   Stock B207 internals. Ported head, stronger valve springs and sharper cams. The 364 was at around 7600.   Also look at obdtuner update 2.7.10 (the reason why our logging cuts at around 7k, thus not showing/logging full potential over 7k.) Exmantaa and his mate use HP tuners who do not have that issue.  

  What's in 2.7.10 changed for the power logging?   The 360HP (364 road - 354Hp on a MAHA dyno, whatever...) on our 2.0's is made at the 7800rpm set limiter with some ignition tweaking, but we're thinking about upping that to 8K as it revs so smoothly now. (And noise wise Rob's is not too bad on his 2.5 + kat system!)   But these numbers are optimised on cold-ish weather and with relative short accelerations (3rd gear) runs. (no knock) All mainly done to give us a solid base for where we want to be with the water injection installed.  

Fixed: In the log files the throttle pedal position reached 100% to early.

[Nev]

Worst case Lee can go touring in the mountains with Nev.

 

I'd say that would be the best case (but only if you like miles of open empty un-policed roads with more twists and dips with good visibility than you can shake a stick at).

 

The only hard bits are rolling out of bed early and swerving to miss the rabbits and pheasants (and being very cycle/motorbike aware as there are a few).

 

On my best run I only saw 1 other car in an 18 mile stretch, though that was a bit exceptional, usually you see one every 5 miles or so.

 

This pic is of a 5 mile "mini Pikes Peak", though embarrassingly it seems to have a lorry on it (and another tiny white dot (car?) 1 mile further up - it was about 10 AM and jammed up with traffic by then I think

 

Edited by Nev, 01 December 2016 - 05:06 PM.

[smiley]

You're Lucky to have the option.

I would loose my license in 15 min over here in NL.

 

[Exmantaa]

Eaton TVS compressor maps:

 

1320:

 

1900:

 

 

[Nev]

I understand what your pointing at Exmanta, it does appear to puff out 40% more volume (and at a slightly higher PR). But in practice I think all that will happen at low revs is a (relative) lack of torque and some fuel inefficiency. As with a big turbo, you have to sacrifice the bottom 1/3rd of the RPM to gain in the top 1/3rd (unfortunately). Loosing say 50 ft/lb of torque at 2000 RPM to gain 100 ft/lb at 7000 RPM is worth it (IMHO) as when you want to drive fast you are never at 2000 RPM anyway. If he keeps moderately reserved cam timings I think the loss of torque low down wont be too much, and ultimately after 1000 miles of driving it I'm sure Lee will automatically/instinctively adapt to the rising torque line anyway (just like the stage 4 VXT boys have to! Just kidding, this will be loads smoother)

 

Edited by Nev, 01 December 2016 - 05:20 PM.

[Exmantaa]

Point is that a supercharger is mechanical driven and a big 1900TVS simply takes more power to turn than a 1320TVS... (Not to mention the extra weight of it compared to the direct fit LSJ-TVS1320.)

 

I have to read-up on my compressor map calculation skills, so if anybody is more into this, please chime in.

But to make 500HP (will be ~550 inside the engine) the bigger TVS is off course more in it's element.

They say for 550HP you need to flow about 825CFM air, which is 0.3894 m3/s = 1400m3/h. (Google this)

Now to flow this 0.3894 m3/s with a 2400ccl engine at say 7800rpm, you're talking a pressure ratio of 2.5. (@100% efficiency, the heat will make things worse...)

 

But what if I'm cornering and only want this SC engine to make 150Hp accelerating from 4000rpm. Or say 350Hp on higher revs on a not so perfect track surface? Looks like your then much more efficient with the 1320

[Nev]

Everything you say seems correct there, except there is no need to let the PR to max out under partial load IMO. To take 2 examples (that you used):

 

1. For full load (ie booting it down a straight), then PR wants to be maxed out for high torque and ramming as much air in as possible.

2. For partial load (ie cornering at 150 HP), when the accelerator input maybe 20% say, then have that linked to a bypass valve that will bleed off the PR, thus lowering the IATs.

 

This would be similar to a turbo waste gate situation, where the accelerator is mapped to boost demand. In this case when the accelerator is only partly pressed, the waste-gate can be made to open "artificially" (via a solenoid) to bleed off excess boost when not at 100% load. This mapping logic is used on the VXT (and 101 other TC'ed cars).

 

BTW I am just thinking how I would approach this issue off the top of my head, maybe the high powered supercharged mappers have some other ways to handle this that are more elegant or better suited.

 

An alternative is a really basic boost/mechanically triggered system could open/throttle the bypass valve at say 1.5 PR using a simple spring loaded bypass valve (a Forge valve with 2.5 Bar spring for example). This could work independently of the ECU and map if you wanted, thus meaning the PR could never ever get high enough to cause serious IAT issues, but still allows the SC'er it's huge flow for massive power at the top RPM end.

 

I also doubt fuel economy is a high up on Lee's list of priorities, I bet the fuel costs will be lower than his build cost even if he drove 25,000 miles. I get 25 MPG at my very best (motorway cruising) and only about 3 MPG when booting it, but even though I'm a tight-wad the smiles outweigh the costs.

Edited by Nev, 01 December 2016 - 08:29 PM.

[Exmantaa]

Partial load on our SC's is made after the half-closed throttlebody and maybe with a partially open bypass valve (that circulates air back to the CS inlet.)

 

Need to dive more into these map calculations, but it's easy to see that for these power levels on such a small engine volume the needed pressure ratio is way out of the comfort zone for a TVS. That's where a real air compressor (turbo/centrifugal/twin screw SC) starts to shine.

Or max out the engine to 3.0 litres...   

[Nev]

it's easy to see that for these power levels on such a small engine volume the needed pressure ratio is way out of the comfort zone for a TVS.

 

I think it will just mean (relatively) less torque if you boot it at low revs (and higher charge temps for 1 or 2 seconds if the setup allows a PR of 2.7 or whatever) until the RPM comes up sufficiently for the cylinder demand/consumption to equalise more and the middle of the map is reached.

 

I guess it might feel a bit like TC'ed lag, or more likely just a bit "weedy" until at mid RPM. His torque line will certainly not be flat like the smaller SC'ed carz (unless he artificially caps the boost).

 

What is almost a certainty is that VE will be at some insane RPM level (like 10,000 at a guess if his valves open enough), which is highly unusual for any car engine.  

Edited by Nev, 01 December 2016 - 08:56 PM.

[Nev]

Anyway, lets not put him off (!), I for one will be thrilled to see this thing move like greased lightning. With adequate traction he will be faster than a Bugatti Veyron up to at least 100 MPH, and way way faster than anything standard in a Porsch or Lambo showroom.

 

Just goes to show what a "man in his shed" can do compared to the big companies, circa £50,000 car roughly as fast as £1,000,000 car. Stuff like this sometimes leads to a nice career change too, Jon at Courtenays was originally one of their customers believe it or not, learning as an amateur but changing it to professional. I too have been offered a job off the back of my own Nipper project, as have a couple of others like chris_uk and SizTenBoots etc.

Edited by Nev, 01 December 2016 - 09:07 PM.

[The Batman]

you will never put Lee off, hes an animal and will be happy to wheel spin everywhere

[Nev]

Partial load on our SC's is made after the half-closed throttlebody and maybe with a partially open bypass valve (that circulates air back to the CS inlet.)

 

 

My suggestion would require the bypass valve to be located after the supercharger (but before the inlet throats to the cylinders). I suppose you could drill and tap into the aluminium under the SC somewhere (if it doesn't already have an outlet for this). You have to be careful about it's location, as you'd need to avoid some runners getting more charge than others due to a single outlet that was say further away from cylinder 1 than cylinder 4. Maybe 2 or 3 outlets would be better.  

Edited by Nev, 01 December 2016 - 09:06 PM.

[Graeme Lambert]

Top work Lee. Looking forward to seeing the results of this one Sent from my SM-G930F using Tapatalk

[CHILL Gone DUTCH]

Exmantaa's mate speedster4fun's car. He does not post much.   They are both working on their timing atm (though exmantaa uses a 2.0 lsj, and speedster4fun uses the B207)   Stock B207 internals. Ported head, stronger valve springs and sharper cams. The 364 was at around 7600.   Also look at obdtuner update 2.7.10 (the reason why our logging cuts at around 7k, thus not showing/logging full potential over 7k.) Exmantaa and his mate use HP tuners who do not have that issue.  

  What's in 2.7.10 changed for the power logging?   The 360HP (364 road - 354Hp on a MAHA dyno, whatever...) on our 2.0's is made at the 7800rpm set limiter with some ignition tweaking, but we're thinking about upping that to 8K as it revs so smoothly now. (And noise wise Rob's is not too bad on his 2.5 + kat system!)   But these numbers are optimised on cold-ish weather and with relative short accelerations (3rd gear) runs. (no knock) All mainly done to give us a solid base for where we want to be with the water injection installed.  

Fixed: In the log files the throttle pedal position reached 100% to early.

Do we think that the 80mm pulley is a good optimum for a 7500-8000 rpm limit ? I've noticed the smaller pulleys are good at lower Rpms ( coming out of corners ) but the bigger pulleys are more than up to the job and higher rpms with less boost and iat. Just thought I would ask what others opinions are now people are finding some good optimum levels of ignition on there engines ??

[CHILL Gone DUTCH]

It's all a compromise I guess Also wondering what lee has pulley wise on the 1900

[vocky]

What will be the max rpm of this with the 2.4 crank (98mm throw)?

 

 

7525 rpm is the safe maximum speed.

 

I did run mine at 7900 rpm for a few years, but had it reduced to 7650 rpm earlier this year to be on the safe side.

 

Having the bottom end fully balanced is the key to a longer engine life span with these tweaked LE5 engines.

[Exmantaa]

7525rpm is about 24.6 m/s mean piston speed with that long crank throw, the same piston speed as 7800rpms does with a 2.2 crank.

(Was talking to Rob this morning and as the 2.0's can rev to 8575rpm to achieve those velocities, he's going to up his limit a bit further. )

 

 

 

[leevx2.2]

well as the 1900 Harrop has an internal bypass valve i had to cut and blank of the intake manifold ,so got the chop saw out and chopped it of and made a blanking plate and got a local company to weld it up for me .
Top company charged  me £20 to weld the dual pass and blank it of  bargain    ,then i drilled and tapped the holes i had in the charger neck and blanked them of with a few bolts and thread lock .
Need to start buying bits but Christmas might get in the way lol.
 


 

Edited by leevx2.2, 14 December 2016 - 08:05 PM.

[The Batman]

Fits perfect!

[leevx2.2]

Fits perfect!

yes loads of room  but the back bolts are a  bitch to get to  though