V8Racing Rob builds a stormer!!
Discussion
Have put this in general TVR as it's of interest to anyone runing a RV8 TVR and thinking of engine work ..
Rob (V8Racing) and Phil "megasquirt guru" (DaxTojeiro) brought in a Chimaera today running a 5.5 litre engine and megasquirt ecu. It now holds the record for the highest RV8 engine i've yet seen .. a storming 374.6bhp and 420odd lbs.ft
It's so good it produces as much hp at 3500 revs as a very good std 5 litre TVR RV8 does at peak! 280bhp at 3500 rpm!
Fantastic!!
Rob (V8Racing) and Phil "megasquirt guru" (DaxTojeiro) brought in a Chimaera today running a 5.5 litre engine and megasquirt ecu. It now holds the record for the highest RV8 engine i've yet seen .. a storming 374.6bhp and 420odd lbs.ft
It's so good it produces as much hp at 3500 revs as a very good std 5 litre TVR RV8 does at peak! 280bhp at 3500 rpm!
Fantastic!!
Thats fantastic!
.Whats the spec of the engine regarding heads,cam etc?I just looked through the megasquirt log of the power runs and increadably the engine was restricted by the act triple intake plenum, there was still 4Kpa vacuum in the manifold at 6000rpm!!!!! Thats around a 4% restiction in theory,
Phil
Phil
Edited by daxtojeiro on Friday 21st July 20:27
daxtojeiro said:
I just looked through the megasquirt log of the power runs and increadably the engine was restricted by the act triple intake plenum, there was still 4Kpa vacuum in the manifold at 6000rpm!!!!! Thats around a 4% restiction in theory,
Phil
I thought the engine was stdPhil
Can we have the full spec please? Also why do the extra 500cc make disproportionately more horsepower?
Thirdly,i want one!!!Like someone already said-how much please?
Rob-i mailed you recently,could you mail me your no.please
daxtojeiro said:
I just looked through the megasquirt log of the power runs and increadably the engine was restricted by the act triple intake plenum, there was still 4Kpa vacuum in the manifold at 6000rpm!!!!! Thats around a 4% restiction in theory,
Phil
Phil
Edited by daxtojeiro on Friday 21st July 20:27
Phil : is the take off for the pressure reading done in an area of high air speed? could it be the dynamic pressure reduction you're measuring?
ie pressure drop equal to 0.5*density*velocity squared assuming no static pressure drop .. if you really want to measure the pressure drop you'd have to position the probe into slow moving air like into the heart of the plenum. Where was the takeoff positioned?
Edited by trackcar on Friday 21st July 21:47
Jooles,
the take off for the map is on the back of the plenum, where the idle valve assembly is, so Id think that was pretty accurate to be honest, I can send you the log, it starts out at atmosphere (98KPa) and starts to drop off with rpm around 4000rpm, I bet its the fact that the act intake is tapered to fit the AFM (obviously this engine doesnt have that), if it was wider at the intake point and a thicker bit of pipe to the filter it would be better,
Phil
the take off for the map is on the back of the plenum, where the idle valve assembly is, so Id think that was pretty accurate to be honest, I can send you the log, it starts out at atmosphere (98KPa) and starts to drop off with rpm around 4000rpm, I bet its the fact that the act intake is tapered to fit the AFM (obviously this engine doesnt have that), if it was wider at the intake point and a thicker bit of pipe to the filter it would be better,
Phil
trackcar said:
could it be the dynamic pressure reduction you're measuring?
Have you calculated the dynamic pressure drop for that throttle area? I have a suspicion that this plays a big part in the gains that multi throttle plenum setups seem to bring. I can't remember the figure I calculated for mine when I was looking into the pressure drop, but I remember thinking that the theoretical pressure drop accounted for the bulk of the actual pressure drop I measure.
In terms of measuring still/moving air, unless you have a pitot tube in the throttle body I think you'll be seeing total minus dynamic, because I very much doubt there's any pressure recovery in the plenum.
jellison said:
Same engine as Topsparks that made 330bhp and 365ft/lb on Roller in Norfolk then!
The strange thing is john, when i had topsparks on our dyno that showed more or less the same figures as the one i have just had at trackcar, the horsepower was down about 20 bhp which is what i would expect for the exhaust, both engines are similar but not the same but certainly not different enough for the big difference in power output, being a realist i think the bhp is correct on trackcars dyno, the torque i was expecting to be around 400 ftlb, as a comparison a 5.2 on a normal large throttle plenum with a 404 etc in it would make around 325-330bhp, add to that the carbon plenum +30 bhp, 300 cc+15 bhp, mappable ign/fuel another 15 bhp, thats an extra 60 bhp so it should be making 390 bhp, those figures of topsparks are just wrong, even you have commented on how fast the car is, i know james is gutted at the figures but even he said he has justed wasted his mates vantage!! last time i spoke to james i told him to take it to srr and get charley to do a power run on the car i would even pay for it, at least there you can get a good comparison from other cars.
jellison said:
Same engine as Topsparks that made 330bhp and 365ft/lb on Roller in Norfolk then!
I take it it's emeralds rolelrs you're referring to ..
Our race car was mapped at emerald and it makes a smidge over 380bhp on dave's rollers .. on mine it makes 389bhp so we're not a million miles away in comparison terms (about 2% which is what I told Rob the difference is between the two rollers, we're also 2% out from Nobles rollers so I'm inclined to believe all these good roller set-ups red pretty much the same in real world terms ie to within 2%) . Maybe topsparks killed it doing all those burnouts and doughnuts
GreenV8S said:
Have you calculated the dynamic pressure drop for that throttle area? .
I haven't .. can you use straight forward bernouille? how do you calculate the density when air is elastic .. as it's under vacuum it's effective density reduces surely ..?
If you let me know how you calculated yours I'll have a bash at it.
daxtojeiro said:
Jooles,
the take off for the map is on the back of the plenum, where the idle valve assembly is, so Id think that was pretty accurate to be honest, I can send you the log, it starts out at atmosphere (98KPa) and starts to drop off with rpm around 4000rpm, I bet its the fact that the act intake is tapered to fit the AFM (obviously this engine doesnt have that), if it was wider at the intake point and a thicker bit of pipe to the filter it would be better,
Phil
the take off for the map is on the back of the plenum, where the idle valve assembly is, so Id think that was pretty accurate to be honest, I can send you the log, it starts out at atmosphere (98KPa) and starts to drop off with rpm around 4000rpm, I bet its the fact that the act intake is tapered to fit the AFM (obviously this engine doesnt have that), if it was wider at the intake point and a thicker bit of pipe to the filter it would be better,
Phil
We have tried bigger air-box intakes in the past up to 95mm ( the current is 80mm) and larger throttles up to 54mm, i haven't seen any benefits (yet) if there is a requirement for a larger intake i'll produce it, are you sure it's not the hose to the filter causing restricting ?
Gassing Station | General TVR Stuff & Gossip | Top of Page | What's New | My Stuff