Engine building discussion

[skitchin]

Call it an obsession or just a past time, but I've been reading on engines/building/general dynamics(despite the fact I've never even done a head gasket job). I have a bit of a pipe dream of building a racing style motor at some point down the road. I know Formula 1 engines rev to insane speeds of up to 18,000 RPM, and that this is a large part of the sound. But I'm curious about the other factors that play a role. At no point through the rev range does a F1 engine sound like any traditional automobile engine.

[video=youtube;Czw1pB6ZDRM]http://www.youtube.com/watch?v=Czw1pB6ZDRM

 

What do you suppose gives F1 engines the unique sound? I've been reading up on compression ratio, bore/stroke ratio, rod/stroke ratio, piston dwell, piston speed, power strokes per second, etc. From what I gather, F1 engines typically run around 17:1 compression, up to 2.5:1 bore/stroke ratio, and over 2:1 rod/stroke ratio. Anyone have some knowledge to drop on me?

Edited July 12, 2013 by skitchin

[RobertISaar]

if you're looking to dramatically change the sound of an engine, cam the living hell out of it.

 

F1 engines run STUPID amounts of power through really small displacement engines.

 

 

 

combine those two factors and you have a lot of your solution.

 

of course, exhaust at every step of the way is very important to the sound as well. the headers are HIGHLY optimized to make power only within the rev band that the engine will experience after 1st gear.

 

every part in a F1 engine is designed much the same way, there are very few to no compromises that are taken that would otherwise be required of a street-driven vehicle. basically: "does it make more power in the 12,000-18,000 RPM rev band than what we're currently using? if so, how does it effect fuel consumption?"

 

of course, the F1 organization sets up guidelines as to what is and isn't allowed, so they have to optimize everything possible within those boundries.

 

 

 

here is more reading on the exhaust, since i'm sure you want to stare at walls of text.

 

http://www.f1technical.net/forum/viewtopic.php?f=4&t=10436

[Garrett Powered]

I use race parts but don't intend on changing the RPM range too much at this point. I still have a torque monster setup like it was intended for bullying around all the little import cars.

[RobertISaar]

honestly, you wouldn't be able to extended the rev range much either... 282s have problems shifting above 7K, i imagine 284s can't do much higher. the automatics that will bolt up to anything installed from the factory in a W are even worse.

 

i guess if you were to be okay with ~1.5 second shift times to try and keep the synchronizers alive, it could be done, but that takes away a lot of fun.

 

 

 

another effective method of exhaust note modification are 180* headers. i'm sure you've come across the subject in one form or another, but the idea is to pair cylinders that have equal amounts of time between firing events to maximize scavenging. a side benefit of this is the way it makes the engine sound.... IIRC, there is a 2.8 fiero(in thailand?) that did this(it's on youtube.... somewhere), sounds strange for a 60V6. it's an absolute nightmare to package with a transverse driveline.... and not much better with a standard longitudal layout. you get some really odd routing. if you were to do it with a 60V6, you would basically look at your coilpacks to see which cylinders need to be connected(1/4, 2/5, 3/6). with a firing order of 1-2-3-4-5-6 and the odd cylinders on one bank and even on the other, it's a better situation than most engines, since you'll largely have 3 of the same pipe "sets" to connect the cylinders. getting the distances equal is a lot easier with RWD.

 

certain V8 engines this is an absolute PITA to do due to firing order, requiring crossover tubes on certain cylinders and pairing of two cylinders on one bank on others....

[RobertISaar]

so i had a crazy thought.... why reinvent the wheel when you can adapt another?

 

so there are engines you can buy right now that are pretty F1-like.... low displacement, high revving, can sound awesome, almost always ITB....

 

crotchrockets.

 

Adam's triumph for example, sounds great, displaces 675cc, 12.65:1 compression, EFI, 6 speed close ratio trans, makes 123HP at 12,500(that's almost 200HP/L), 53 lb-ft at 11,750.... sounds pretty similar to how F1 engines are setup. obviously, you'll have to work around adapting a bike engine for use in a car, but i've seen a hayabusa powered go-kart before, so it has to be possible with enough work on mounts/exhaust/etc....

 

of course, you may need more than one engine to power a car(still need torque to move something as hefty as a W).... which brings up the interesting possibility of having multiple engines when needed, but cutting down to only one when not. then adapting a chain drive to power the front(or perhaps rear/AWD?) wheels. then it's pretty much good to go.

 

 

 

EDIT: yet more crazy thought: by doing this, you'll already have a sequential 6 speed manual transmission for more F1 inspired goodness.

Edited July 13, 2013 by RobertISaar

[skitchin]

I'm open to pretty much all possibilities between chassis and motor platform... mr2 does come to mind >_< lol. Even though the one I had was shit I still saw good things somewhere in there. Even a Hayabusa engine is a bit underpowered(albeit not for that displacement). But that is definitely along the right line of thinking, especially having a trans that technically could stand up to it - though everything would need a lot of custom fabrication... But apparently it is a thing:

[video=youtube;6NhH7_Fx1fE]

 

Curious how it's built but it seems to be doing just fine - gonna read up on this stuff.

[skitchin]

LIKE THIS

 

[video=youtube;NR1MonpwuuM]

[skitchin]

Looking over a couple different makes of 1000cc motors, in the last few years they've all started running shorter strokes and higher compression. CBR1000RR looks interesting, 1.4:1 Bore/Stroke ratio and a Rod/Stroke ratio of 1.9:1

http://en.wikipedia.org/wiki/Honda_CBR1000RR#Specifications

http://www.aperaceparts.com/tech/2008hondacbr1000rr.html

[skitchin]

I really wish there were better resources around on engine specs. Maybe I just suck at finding stuff. I can get info on the bore/stroke of a motor all day, but when it comes to rod length or block deck height fuck all.

 

GM Quad4 and some other DOHC I4 series are looking kind of interesting. Apparently there were modified race versions of these motors that put down some serious power, and the engine was also used in Oldsmobile's experimental Aerotech vehicle

http://en.wikipedia.org/wiki/Oldsmobile_Aerotech

Sadly the only video I can find with the car even running is this cheesy commercial which may have dubbed the audio sample

[video=youtube;xMG9Tjleu-Y]

[RobertISaar]

some info just doesn't exist on the tubez... i do have some rather hard to source info on the Q4... anything specific you're looking for?

[skitchin]

Looking at the LD9 iteration atm. Block deck height is mainly what I need. I've figured out I can look through summit at pistons and rods to fill in some of the blanks.

 

Also this is an old pic from when I was cleaning my garage, but though about it a few minutes ago when I was doing the same thing.

[skitchin]

OOoh, also, head gasket thickness, head combustion chamber cc.

[RobertISaar]

there seems to be ~3 different definitions of deck height used on teh intertubes....

 

smallest space between top of piston and bottom of combustion chamber(which i refer to as quench height)

length of centerline of crank at TDC to top of the bore

length of center of mains to top of the bore

 

i THINK the second is what you're looking for?

[RobertISaar]

actually, i'll just dump what i have, pick out what you need.

 

common to both the HO and LO Q4:

3.622 bore

3.35 stroke

3.75 headgasket bore(an estimate here)

.047 headgasket thickness

48cc combustion chamber volume

.001 top of piston to top of bore

 

HO only:

10:1 compression via piston with 6cc dish

.410 cam lift both intake and exhaust

ICL = 108

ECL = 112

LSA = 110

247* duration at .005 lift

213* duration at .05 lift

(looks like same cam profile used on intake and exhaust cams?)

 

LO only:

9.5:1 compression due to 9cc dish in pistons

.375 lift on both i/e

200* duration at .05 lift(no idea on .005)

 

W41 HO:

mostly standard HO, but:

ICL 108

ECL 108

LSA 108

258* at .005

219* at .05

 

 

 

i might have more laying around somewhere...

[skitchin]

Hrm there's a LOT of varying info on the HO Quad4 out there. To the point where it's pissing me off on an OCD level LOL. There does seem to be a way to build the Quad4 with internals similar to a 1000cc streetbike motor. The difference in bore is only just over half an inch - but there's a few inches difference in block height. CBR1000RR redlines at 13,000 RPM and with a stroke of ~2.17 piston speed is 4700 FPM. If I could shorten the quad4's stroke to something like 2.6, revs for equivalent piston speed would be about 10,500 RPM. But I'm also guessing longer rods are weaker.

 

The shorter the stroke the less piston speed the faster the revs. F1 cars run a 1.56in stroke which is partly how they can get away with 18,000 rpm

Edited July 15, 2013 by skitchin

[RobertISaar]

rev happy and slower engines both seem to like large rod/stroke ratios... helps keep the piston skirt off of the cylinder wall, especially with a longer stroke engine, since the rod angle can get quite extreme in those situations.

 

the "loss" in strength from simply being a longer rod, i wouldn't mind that compromise, since it will potentially keep the piston alive longer. if rod strength were an issue, let it break, analyze why, make a better version.

 

 

 

and yes, i know all about Q4 info being wildly different. a lot of GM's hot relatively consumer level engines from the early/mid 90s seem to suffer the same problem. all 91-93 LQ1 have the same compression ratio, regardless of being auto/manual. the aurora 4.0 being a "cheapened" version of the northstar with a different fueling system is a lie. there are all kinds of gossip turned "fact" about a lot of them. i made every effort to cross-reference what i found online with GM documentation in one way or another. very little "make it work" values were used.

[skitchin]

Hrm Q4 would be decent to build up but choices for parts will probably be slim to nill... I have to say it's tough to ignore the idea of putting a 1000cc bike engine in a car. It's all right there built for it and ready to go. Some wizardy happens and voila? Lol Torque beyond lacking as would be expected, but the pickup seems pretty good and the sound is unbelievable.

[video=youtube;YYxVKZEt5MU]

 

 

 

 

 

Edit: A chevy v8 would be readily available + aftermarket support. There's plenty of places that make cranks down towards the range i'm looking for too. Would think more weight harder to balance so less revs, but, I guess the F1 v8's do okay? But I4 vs V8 = twice as many pistons and stuff to buy heh

Edited July 15, 2013 by skitchin

[RobertISaar]

well, if you manage to stuff anywhere from 2-4 engines under the hood, you'll solve the lack of torque issue, in addition to sounding like you're racing yourself.

[skitchin]

This site does give me some hope as far as v8's go:

http://www.kingscrankshaft.com/kings_crankshaft_llc_002.htm

 

All the way down to 2.5in cranks for various chevy engines, which should be good for 10K+ revs theoretically. 4700FPM or somewhere around there seems to be the red-zone for piston speeds. This was true of the CBR1000RR, Formula 1 engines, even the LS7 - though many cars are rated much more conservatively.

[RobertISaar]

"chevy V6" cranks?

 

wonder if they mean the 60V6 or the 4.3?

 

also, you can have a crank welded and offset ground to increase stroke.... i don't see any reason why the same couldn't be done to shorten it.

[skitchin]

Hmm it seems I could acquire a 1000cc bike engine and even rebuild the thing for far cheaper than it'd cost to buy and redesign whatever other engine I found. Biggest problem though is all the videos I've seen the bike engines seem to barely even get the car rolling, they're basically neutral bombing the thing just to get it to launch, so that makes me wonder about putting a 1L in a car. But then I can't seem to find rods rated above 7500 RPM, any suggestions there?

[RobertISaar]

stock gen2/3 60V6 rods take 7000... as evidenced by the fact that the same rods used in the LQ1 are used in everything else gen 2/3.

 

going above that, tricky.

 

 

 

also, since you're going this far, why not pick out some more tech.... electric assist. since low RPM power has never been a strong point of a high-strung bike engine, use a different form of power when necessary. have some electric traction motors help propel the car. one of the biggest draws of the electric motor is the fact that it has full power at all speeds. you could go from a 1L engine making ~60 lb-ft to over 300-400 when the electric motor is assisting the gas engine.

[skitchin]

Not a bad idea...though definitely beyond me how to actually accomplish that... Wonder if supercharging would help or hurt the low power torque/launch issues.

[Mach 5]

Not too sure on the actual physics that create F1 sound but here is my AE86 20v itb videos...

 

I personally really like the 355f1 engines they also have 5 valves per cylinder and have great sound kinda like F1 very similiar to my Toyota. I have pictures on request.. of the cylinder head up close my machinist had one of these engine in the shop since it threw the timing belt.

[Galaxie500XL]

This entire topic is full of win....good stuff here.