Rotary Swap Help
Discussion
Hi All,
I recently bought a Radical SR8 rolling chassis on the cheap for which I am finalising a deal on a Hewland sequential transaxle which is limited to 325Nm/240lbft max. torque. The 'box was sourced with a view to installing a rotary engine, being the same one used in Formula Mazda / Star Mazda in the US so there is good support available and an off-the-shelf billet ally bell-housing which is handy.
Now, for the engine itself.....
I need to keep it N/A to keep the torque under the limit of the gearbox. I would actually like a little headroom to that peak torque figure for the sake of gearbox reliability. This won't be a torque monster but doesn't to be. I would like it to be high revving screamer in line with the SR3/SR8 cars but with more than the 270bhp that the SR3 comes with and without the 40hr rebuilds! 300bhp is my target for now.
My problem is that I don't know which way to jump - 13b or Renesis?
For the former, it seems 300bhp and higher is easily doable with peripheral exhaust ports but will require upgraded everything with costs to suit.
For the latter, I have found a freshly rebuilt Renesis engine with dry sump, microtech ECU and a load of other bits for a very good price [roughly the cost of rebuilt stock lump] which on paper looks to be just the ticket but then I can't seem to find much info. relating to race building/tuning the Renesis.
The seller states it was pushing out 260bhp prior to rebuild on essentially a bog standard engine [std. rotors and porting] with the oiling system junked in favour of the dry sump set-up, light flywheel and a standalone ECU with wide band lambda. Given he used the same transaxle I am buying has verified ratios, rev limits, speeds etc. to give me that warm feeling that this will work. Trouble is, I want 300bhp....
I have seen that Ryan Rotary Performance has done a hybrid peripheral port on this engine for road use but they have yet to respond to my emails. I'm also not getting very far with trawling the rotary forums as all discussions are based around streetability which isn't my concern, so thought I would try here before joining one to ask and subsequently get flamed.
Is a 300bhp race-biased Renesis a pipe dream or reality and what work is needed to get there? Would it be easier to go 13b or just accept an honest, reliable 260-270 out of the Renesis?
Keen to have a good discussion around pros, cons and costs. Happy to take N00B flack as I am one when it comes to rotaries. My budget is realistic but not to be spunked on chasing ghosts. Build thread to follow once the main bits arrive.
TL:DR - I want to shove a rotary in a radical SR8 rolling chassis. N/A 13b or Renesis, which route would you take?
I recently bought a Radical SR8 rolling chassis on the cheap for which I am finalising a deal on a Hewland sequential transaxle which is limited to 325Nm/240lbft max. torque. The 'box was sourced with a view to installing a rotary engine, being the same one used in Formula Mazda / Star Mazda in the US so there is good support available and an off-the-shelf billet ally bell-housing which is handy.
Now, for the engine itself.....
I need to keep it N/A to keep the torque under the limit of the gearbox. I would actually like a little headroom to that peak torque figure for the sake of gearbox reliability. This won't be a torque monster but doesn't to be. I would like it to be high revving screamer in line with the SR3/SR8 cars but with more than the 270bhp that the SR3 comes with and without the 40hr rebuilds! 300bhp is my target for now.
My problem is that I don't know which way to jump - 13b or Renesis?
For the former, it seems 300bhp and higher is easily doable with peripheral exhaust ports but will require upgraded everything with costs to suit.
For the latter, I have found a freshly rebuilt Renesis engine with dry sump, microtech ECU and a load of other bits for a very good price [roughly the cost of rebuilt stock lump] which on paper looks to be just the ticket but then I can't seem to find much info. relating to race building/tuning the Renesis.
The seller states it was pushing out 260bhp prior to rebuild on essentially a bog standard engine [std. rotors and porting] with the oiling system junked in favour of the dry sump set-up, light flywheel and a standalone ECU with wide band lambda. Given he used the same transaxle I am buying has verified ratios, rev limits, speeds etc. to give me that warm feeling that this will work. Trouble is, I want 300bhp....
I have seen that Ryan Rotary Performance has done a hybrid peripheral port on this engine for road use but they have yet to respond to my emails. I'm also not getting very far with trawling the rotary forums as all discussions are based around streetability which isn't my concern, so thought I would try here before joining one to ask and subsequently get flamed.
Is a 300bhp race-biased Renesis a pipe dream or reality and what work is needed to get there? Would it be easier to go 13b or just accept an honest, reliable 260-270 out of the Renesis?
Keen to have a good discussion around pros, cons and costs. Happy to take N00B flack as I am one when it comes to rotaries. My budget is realistic but not to be spunked on chasing ghosts. Build thread to follow once the main bits arrive.
TL:DR - I want to shove a rotary in a radical SR8 rolling chassis. N/A 13b or Renesis, which route would you take?
Hi there,
Long time lurker, first time poster.
In terms of N/A - the best Renesis engines in the UK are currently in the 210/215whp range (so probably somewhere about 250bhp-ish). Carl Ryan's PP Renesis developments have the potential to eclipse this, but has yet to be proven. As an aside, Haywoods Rotary have done at least one PP Renesis that I know of, which has a stated target of 260bhp+, but got very poorly when dyno'd and is currently being tinkered with. So, if you want 300bhp N/A, you'll be breaking new ground in the UK. If you're comfortable doing this then partnering with someone like Carl Ryan could be the way to go (I believe Haywoods have said they wouldn't do another Renesis like this). However, you're a good 50bhp above what's already been proven in this country ... so it will be bit of a journey into the unknown.
I know you say you've struggled to get hold of Carl, but I've always found him very easy to communicate with via the RX8 Owners Club forum. He's also fairly active on Facebook. He made the shortlist for my Renesis rebuild, and was very helpful answering my questions and talking me through the different options. In the end, I went with another company, and had a full Bridgeport, which after a mapping session, made 194whp on their hub dyno (standard engines tend to make about 165whp on the same dyno).
Of the options you put forward, I think a 13b would be a more suitable base for your project, but you may like the uniqueness that comes with being a pioneer in pushing a UK N/A Renesis to new levels.
That said, if it were me and I wanted a 300bhp N/A rotary, I'd be looking straight to a 20b ... there are a couple of engines kicking about the UK at the moment. The one I know of is being kept N/A and is being installed in a Time Attack class winning RX8 as the owner wants more power to go and compete in higher classes.
Long time lurker, first time poster.
In terms of N/A - the best Renesis engines in the UK are currently in the 210/215whp range (so probably somewhere about 250bhp-ish). Carl Ryan's PP Renesis developments have the potential to eclipse this, but has yet to be proven. As an aside, Haywoods Rotary have done at least one PP Renesis that I know of, which has a stated target of 260bhp+, but got very poorly when dyno'd and is currently being tinkered with. So, if you want 300bhp N/A, you'll be breaking new ground in the UK. If you're comfortable doing this then partnering with someone like Carl Ryan could be the way to go (I believe Haywoods have said they wouldn't do another Renesis like this). However, you're a good 50bhp above what's already been proven in this country ... so it will be bit of a journey into the unknown.
I know you say you've struggled to get hold of Carl, but I've always found him very easy to communicate with via the RX8 Owners Club forum. He's also fairly active on Facebook. He made the shortlist for my Renesis rebuild, and was very helpful answering my questions and talking me through the different options. In the end, I went with another company, and had a full Bridgeport, which after a mapping session, made 194whp on their hub dyno (standard engines tend to make about 165whp on the same dyno).
Of the options you put forward, I think a 13b would be a more suitable base for your project, but you may like the uniqueness that comes with being a pioneer in pushing a UK N/A Renesis to new levels.
That said, if it were me and I wanted a 300bhp N/A rotary, I'd be looking straight to a 20b ... there are a couple of engines kicking about the UK at the moment. The one I know of is being kept N/A and is being installed in a Time Attack class winning RX8 as the owner wants more power to go and compete in higher classes.
shirt said:
Hi All,
TL:DR - I want to shove a rotary in a radical SR8 rolling chassis. N/A 13b or Renesis, which route would you take?
I went through some of these issues with WGT automotive developments (Rotary experts) when I had a rotary put in my MX5. (daily driver, not a race car though)TL:DR - I want to shove a rotary in a radical SR8 rolling chassis. N/A 13b or Renesis, which route would you take?
Forced induction > 5psi - use 13B
N/A and forced induction < 5psi - use Renesis (13B-MSP) . Exhaust ports get too hot otherwise.
Their first attempt was with a freshly rebuilt renesis but this didn't even make stock figures on their Dyno. So they tested with some standard cars to be sure and found the renesis in those were even worse. => Dont believe Mazda power figures for the Rx8.
In the end, I went for a streetport by BDC motorsports (US company). WGT did many months of development with it and ended up with 200rwhp. (~240bhp) running on an Adaptronic 1280 ECU. Ran at 9500rpm.
Exhaust backpressure was only 0.5psi. Many different intake schemes were tried and optimised but that's as good as it got.
So I'd be suprised if you could get 300bhp normally aspirated out of Renesis with any port.
If you go 13B, the standard engine in my 2000 RX7 has 300bhp and ~240lbft torque at ~14psi which meets your specs. You wouldn't want the complexity of the twin-turbo setup. A small single would do.
Kiwimazda (PH poster) claimed 275bhp/300bhp out of a 13B N/A race engine can be done.
Rotary Potato: Thanks for the reply, especially as you had to break lurker cover to do so!
I would love a 20b but it seems that these have become very popular in recent years and so costs for donor engines have skyrocketed. I can't justify what I expect will be in the ballpark of £12-14k minimum to build one. I did enquire about the one on racecarsdirect and that has an £18k price tag.
For the Renesis, Mazdatrix in the US have built a hybrid PP engine but using Renesis rotor housings, a very convoluted exhaust arrangement and a ton of intricate bespoke fabrication. I do like the approach of the Ryan build, taking the best bits of the Renesis but using RX7 housings to simplify the exhaust arrangement. Yes it's breaking new ground but seems to make sense from what I have read/learned so far. Hopefully there will be more info. out soon with the car running and a dyno plot.
I do like the idea of having some unique tech. in the car as I junked the initial plan of a Subaru boxer conversion on the grounds that it has been done before into an SR3 chassis. I guess I am swayed by the fact the donor engine I am looking at represents such good value given the extras it comes with. However breaking new ground is one thing, repeatedly breaking engines is quite another.
I think I need a chat with Carl and will also try Haywood's a call [thanks for the heads up, hadn't heard of them before]. Just about to order a copy of 'Street Rotary' as well.
I would love a 20b but it seems that these have become very popular in recent years and so costs for donor engines have skyrocketed. I can't justify what I expect will be in the ballpark of £12-14k minimum to build one. I did enquire about the one on racecarsdirect and that has an £18k price tag.
For the Renesis, Mazdatrix in the US have built a hybrid PP engine but using Renesis rotor housings, a very convoluted exhaust arrangement and a ton of intricate bespoke fabrication. I do like the approach of the Ryan build, taking the best bits of the Renesis but using RX7 housings to simplify the exhaust arrangement. Yes it's breaking new ground but seems to make sense from what I have read/learned so far. Hopefully there will be more info. out soon with the car running and a dyno plot.
I do like the idea of having some unique tech. in the car as I junked the initial plan of a Subaru boxer conversion on the grounds that it has been done before into an SR3 chassis. I guess I am swayed by the fact the donor engine I am looking at represents such good value given the extras it comes with. However breaking new ground is one thing, repeatedly breaking engines is quite another.
I think I need a chat with Carl and will also try Haywood's a call [thanks for the heads up, hadn't heard of them before]. Just about to order a copy of 'Street Rotary' as well.
rotarymazda said:
If you go 13B, the standard engine in my 2000 RX7 has 300bhp and ~240lbft torque at ~14psi which meets your specs. You wouldn't want the complexity of the twin-turbo setup. A small single would do.
Kiwimazda (PH poster) claimed 275bhp/300bhp out of a 13B N/A race engine can be done.
I'm surprised the turbo gives that low a torque figure, interesting. Yes, small but responsive turbo would be ideal and wouldn't impact the regs as I'd be in a class which is essentially run what ya brung.Kiwimazda (PH poster) claimed 275bhp/300bhp out of a 13B N/A race engine can be done.
A guy I know here has a 12a race engine with 240bhp N/A and reckons the same builder can exceed 300 on the 13b.
Hi Shirt,
Now I've broken my lurker status ... in for a penny, in for a pound!
When the Time Attack RX8 owner was publicly canvassing opinions on whether to go 13b turbo, Renesis FI or 20b, his stated budget was in the £5-£7k range. I don't know if he significantly upped that budget to secure a 20b, or if the prices being asked are 'optimistic' and real world sales are being conducted in that ballpark.
I Googled, and it's actually Hayward Rotary - not Haywood - my mistake. I understand from the owner of their PP Renesis that Hayward have found it to be a right pain and would not undertake another such build. I don't know if that's accurate or hyperbole as I've only heard it 2nd hand and not from the company directly.
A friend of mine has (he believes) the most powerful n/a Renesis in the UK, and has partnered with Rotary Revs in Leeds (also the company who did my rebuild). He's currently at about 220whp on their hub dyno and is looking at an aftermarket ECU (from Rotary Revs) and a long header manifold (from Ryan Rotary, in development at the moment - if it makes the expected gains on an independent dyno ... BHR also do one, but couldn't be demonstrated to show any advantage when tested in this country) to try and crack the 230-240whp range. That's getting very close to your 300bhp target.
As a final point, there are many different types of racecar. The most extreme of which can need an engine rebuild every mile or two of full throttle (drag racers). Just because one engine is able to produce 300bhp for a short period of time, doesn't mean that it's suitable for putting in your racecar. I'm sure you've done your homework, but worth checking the engine in question isn't a highly strung drag engine that requires a rebuild every handful of passes.
Now I've broken my lurker status ... in for a penny, in for a pound!
When the Time Attack RX8 owner was publicly canvassing opinions on whether to go 13b turbo, Renesis FI or 20b, his stated budget was in the £5-£7k range. I don't know if he significantly upped that budget to secure a 20b, or if the prices being asked are 'optimistic' and real world sales are being conducted in that ballpark.
I Googled, and it's actually Hayward Rotary - not Haywood - my mistake. I understand from the owner of their PP Renesis that Hayward have found it to be a right pain and would not undertake another such build. I don't know if that's accurate or hyperbole as I've only heard it 2nd hand and not from the company directly.
A friend of mine has (he believes) the most powerful n/a Renesis in the UK, and has partnered with Rotary Revs in Leeds (also the company who did my rebuild). He's currently at about 220whp on their hub dyno and is looking at an aftermarket ECU (from Rotary Revs) and a long header manifold (from Ryan Rotary, in development at the moment - if it makes the expected gains on an independent dyno ... BHR also do one, but couldn't be demonstrated to show any advantage when tested in this country) to try and crack the 230-240whp range. That's getting very close to your 300bhp target.
As a final point, there are many different types of racecar. The most extreme of which can need an engine rebuild every mile or two of full throttle (drag racers). Just because one engine is able to produce 300bhp for a short period of time, doesn't mean that it's suitable for putting in your racecar. I'm sure you've done your homework, but worth checking the engine in question isn't a highly strung drag engine that requires a rebuild every handful of passes.
Hiya,
Let's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting s
t. Hard to find reliable info. so I hope my copy of street rotary gets here quick!
Let's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting s
t. Hard to find reliable info. so I hope my copy of street rotary gets here quick!shirt said:
Hiya,
Let's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting st. Hard to find reliable info. so I hope my copy of street rotary gets here quick!
As there is a 50% increase in power gaining a rotor it should be 50% gain in torque.Let's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting s
t. Hard to find reliable info. so I hope my copy of street rotary gets here quick!shirt said:
Hiya,
Let's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting st. Hard to find reliable info. so I hope my copy of street rotary gets here quick!
I wouldn't hang my hopes on Street rotary helping very muchLet's see if I can keep 100% of your posts on my thread, hehe.
I have seen 2 x 20b's go through ebay uk since I started this endeavour, 1 for £4.5k which was bare bones ex race motor with PP needign afull rebuild, and a rebuilt one 'to your spec - from £8k'. Then there's the 450bhp one on RCD for £18k.
However a quick google reveals one for sale in Indonesia for $3300 fully dressed which now commands my interest.
I see mention of 250bhp wheel hp being possible on the 20b but no mention of torque. Any ideas what this might be? A more reliable, mildly tuned 3 rotor with wider torque band and that noise would be great but then I don't want to have to go back to the drawing board on the transaxle.....
Problem I'm finding with the forums is that there is so much conflicting info. and people chatting s
t. Hard to find reliable info. so I hope my copy of street rotary gets here quick!its worthwhile read but no real revelations in there
if that 20b is in any reasonable shape at all then $3300 US? is a good buy
I'd get that 13B renesis for now to be honest to get you going and buy a used engine to form the basis of a PP exhaust - renesis endplate hybrid build
Edited by 350Matt on Thursday 10th May 13:02
Turned out to be a scam advert. Smelled fishy so i googled a few of their ad descriptions which were c&p’d from various forums and ebay.
I have done the deal on the transaxle which is the key bit. Formula mazda bellhousing is also on the cards so yeah will prob do as you suggest and get the renesis. Get it all running and go from there.
Next stop : build thread!
I have done the deal on the transaxle which is the key bit. Formula mazda bellhousing is also on the cards so yeah will prob do as you suggest and get the renesis. Get it all running and go from there.
Next stop : build thread!
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