High RPM vs Low RPM

I am trying to map out how I'm going to build my car (91 Volvo 745) and besides going NA or Turbo I have realized that there is still several different directions I can go with my build. So my question is what is better for RWD rally? I high RPM motor or a low RPM motor. I plan on going NA (with experience restrictions I kinda have to) and I know based on cam choices I can effect the RPM range where my power lies. But what else effects this? Thanks for any and all help. Oh and a Manual Transmission (hopefully WC T5) if that matters any.

With all due respect, it does not appear that you have enough understanding to specify, let alone build, a competition engine. You need to learn about what you need from an engine and how to get that. Schedule a four hour call with John, 206 431 9696.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Quote
Rallymech
With all due respect, it does not appear that you have enough understanding to specify, let alone build, a competition engine. You need to learn about what you need from an engine and how to get that. Schedule a four hour call with John, 206 431 9696.

The new hours for John Express Engine Building Consulting Service are Thursdays 29 Feb between 12.00 PM and 1.

Poopy ol Robert doesn't recognize a potentially useful question when he sees it, OR he's just tired of watching some of the local boys waste so much time of others then do nothing.

OK you first have to set some limitations...you ain't a Traustfarian are you?
You live at home with mommy like some of those mid coast T-brickers living in the basement at 27 y.o. as a virgin and complain bitterly that cams at Pull-a-part cost $15?

Cause even a full gasket set costs sumpin. So apart from YOUR personal financial and skill limitations, if any......(but we have to consider: BUDGETARY LIMITATIONS.

So, you a trustafarian?

OK OVERARCHING LIMITATION IN MOTOR DESIGN No1:
Fuel you will use always.

The octane of the fuel you will use will set the limit for compression or boost you REDBLOCK can stand.. We are talking Redblock specifically to you and a motor with a 92mm or 96mm bore have different limitations regarding max compression of boost than little thangs with bores at 82mm or 85-86mm. That little design difference seems to fly over the head of all but a couple of guys at Tbricks.

So Gas and bore size set limits on compression, but compression is function of INTAKE VALVE CLOSING, and that can be anywhere a cam designer wants---but its kinda linked to where you want the power..

Next BIG limitation is: What are the GAPS in the gearbox like, how much will the Rs drop on shifts? That limits how peaky the cam can be..
So which T5? (There's really only one gearset to start with).

So: Gas detirmines detonation limit, bore affects det, cam affects compression, which is limited by GAS/det... and cam determines the need for the ratios in the box..

See how its kinda all linked?

Generally speaking in either n.a. or turbo we want to increase torque the thing makes, usually aiming for 60-70% increase.
And we want to to rev a bit cause we are going to shorten final drive, cause that multiplies torque, and compensates for the "gearing UP effect" that tall gravel tires do.


Now in the real _rally world, the best guys I know always obsess about DELIVERY---as broad a powerband as they can, it makes driving easier..
Really kinda like a normal road car powerband but just shifted UP the scale starting at another 50 ft/lbs and going up.

Some events like Mendocino are curve curve curve, and a strong toquey motor that will rev some would be a big advantage over a peaking thang you have to drive like "whaaaa-whaaaaaaaaaaa-(crunch) whaaaa---whaaaaaaaaaaaaaaaaaaaaaaaaaaa---duuuuh uh uh uuuuuh uuuuuuuuuuhhh wa wa whaaaaaaaaaaaaa!

Anyway I need more tea and some breakkie so tell us about your budget, and tools and experience, well talk more.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Personally, if I was building a volvo 740 wagon for rally, it would be a total waste of time if you went with any less than a 9000 rpm and a 6 speed sequential. Just kidding. A stock b230f with a K cam and a header is what I use. The key is gearing.

Quote
alkun
Personally, if I was building a volvo 740 wagon for rally, it would be a total waste of time if you went with any less than a 9000 rpm and a 6 speed sequential. Just kidding. A stock b230f with a K cam and a header is what I use. The key is gearing.

Well Michael Hoche-Mung just saw what a difference that makes at Idaho in his new-to-him ex-Dave White Golf. His previous thing was a reasonably OK 16v with some poop in the motor, new thang is a 2,0 block with an old 8v head, so similar motor powerzez.
Difference was having an actual nice gearset, close ratio gearset. And short final drive..

car just kept acceleration and since it didn't do the whaaaaaaaaaaaaaaaaaaaaaaaaa (snick) duh! uuuuuuuuh uuuuuuuuuuuuuuuuuuuuuuuaaaaaaaaaaaaaaaa--aaaaaa-aaaah whaaaaaaaaaaaaaaaaaaaaaaaaaaaaa thing it just kept going up all the hills.

Of course with a bigger motor like a 2300 Redblock the motor makes more torque and it will not be bothered with a little wider gap than the little VW motor..


And, if it make a goood FAT torque curve, like a properly done turbo motor should, there is even less need for close ratios; nice even steps will be fine.

Yeah the VW is 2450 lbs and a Ovlov wa-goon will be a couple of hundred pounds more but 2300 is 17-18% bigger, 200 lbs is less than 10% more.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Oh christ......I didn't even pick up on the wagon thing. Why haul around that extra weight? As John always says, at least try to avoid the gross mistakes!

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Quote
john vanlandingham

Quote
Rallymech
With all due respect, it does not appear that you have enough understanding to specify, let alone build, a competition engine. You need to learn about what you need from an engine and how to get that. Schedule a four hour call with John, 206 431 9696.

The new hours for John Express Engine Building Consulting Service are Thursdays 29 Feb between 12.00 PM and 1.

Poopy ol Robert doesn't recognize a potentially useful question when he sees it, OR he's just tired of watching some of the local boys waste so much time of others then do nothing.

OK you first have to set some limitations...you ain't a Traustfarian are you?
You live at home with mommy like some of those mid coast T-brickers living in the basement at 27 y.o. as a virgin and complain bitterly that cams at Pull-a-part cost $15?

Cause even a full gasket set costs sumpin. So apart from YOUR personal financial and skill limitations, if any......(but we have to consider: BUDGETARY LIMITATIONS.

So, you a trustafarian?

OK OVERARCHING LIMITATION IN MOTOR DESIGN No1:
Fuel you will use always.

The octane of the fuel you will use will set the limit for compression or boost you REDBLOCK can stand.. We are talking Redblock specifically to you and a motor with a 92mm or 96mm bore have different limitations regarding max compression of boost than little thangs with bores at 82mm or 85-86mm. That little design difference seems to fly over the head of all but a couple of guys at Tbricks.

So Gas and bore size set limits on compression, but compression is function of INTAKE VALVE CLOSING, and that can be anywhere a cam designer wants---but its kinda linked to where you want the power..

Next BIG limitation is: What are the GAPS in the gearbox like, how much will the Rs drop on shifts? That limits how peaky the cam can be..
So which T5? (There's really only one gearset to start with).

So: Gas detirmines detonation limit, bore affects det, cam affects compression, which is limited by GAS/det... and cam determines the need for the ratios in the box..

See how its kinda all linked?

Generally speaking in either n.a. or turbo we want to increase torque the thing makes, usually aiming for 60-70% increase.
And we want to to rev a bit cause we are going to shorten final drive, cause that multiplies torque, and compensates for the "gearing UP effect" that tall gravel tires do.


Now in the real _rally world, the best guys I know always obsess about DELIVERY---as broad a powerband as they can, it makes driving easier..
Really kinda like a normal road car powerband but just shifted UP the scale starting at another 50 ft/lbs and going up.

Some events like Mendocino are curve curve curve, and a strong toquey motor that will rev some would be a big advantage over a peaking thang you have to drive like "whaaaa-whaaaaaaaaaaa-(crunch) whaaaa---whaaaaaaaaaaaaaaaaaaaaaaaaaaa---duuuuh uh uh uuuuuh uuuuuuuuuuhhh wa wa whaaaaaaaaaaaaa!

Anyway I need more tea and some breakkie so tell us about your budget, and tools and experience, well talk more.

Budget= Don't have a trust fund, don't live at mums. Definitely not rich, so I like parts that other vehiculars can donate or I can fab. And this build is going to over a year or two (unless I strike it rich lol) so I definitely want to have a road map for my car so I can build it in stages and not just do things all willy-nilly
Experience= I have always been mechanically inclined, I went to WyoTech and paid attention, I currently work as an independent mechanic, and if I don't know something I am not afraid to look it up or ask somebody.
Transmission= If I'm lucky enough to find one that is not thrashed I would like to get the World Class T5
Engine= Right now it is stock and I finally stopped all the oil leaks on my redblock (believe it or not w/ 260,xxx on the clock, yay). I have a 16v head on my tool chest for it already and I wanted to keep it NA (have to due to class restrictions any).
Gas= I do not put anything in my tank other than Shell or Chevron 91 octane fuel.

Hopefully this helps with answers to my questions.

And thank you John!



Edited 1 time(s). Last edit at 06/24/2012 01:48PM by CaliMeatwagon.

What did you study at WyoTech?

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

I took the core autotech (EMS1, EMS2, Drivetrain, Suspension & Steering) and for the elective I took Street Rod and Custom Fab. I wanted to learn to weld and fabricate. Figured I could transfer that to thicker metals (cages, chassis, etc.). And since I understand how engines work I can learn performance out of school.

Ok, you have more technical knowlege than most! Now take a step back and look at the big picture, look at the reasons for and consequences of the decisions you make.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

OK the 16v is nice, much more resistant to detonation than the 8v combustion chamber, MUCH more valve area with those 2 34mm valves than the 1 44mm, and really excellent ports. The head could be used nearly untouched if you wanted to..

However.

And there's always a however.

There are 2 cams to buy if you want to have any more fun than just a normal road car... and they cost money for cams worth bothering with..

At least aside from the cost, you're lucky cause they are available right here in USA.. In a cooperative venture between the sick and feverish minds at JVAB World R&D cCenetr in Sleazattle WA and the forward thinking Knox Motorsports in beautiful Richmond VA there are full base circle 16v cam cores onto which he can put any profile imaginable.

And in respect to cam profiles, there are lots of chopices..

The one thing is getting compression UP high enough that there is still some fun amount of POP! left when considering intake closing ATDC...
16v pistons and all B230 have dishes in them, and that hurts comp...

See where I'm going?

The 8v head ain't nearly as nice but at least we can mill the everlovin fuck out of one and make comp that way.....

See? Choices.

And 8v needs only one cam---again Knox has those beautiful full circle core I made for him.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
john vanlandingham
16v pistons and all B230 have dishes in them, and that hurts comp...

I don't want to argue with you as you have more experience but when I replaced my head gasket I think my pistons had flat tops (motor is 91 NA). I could be wrong but I really don't remember any dish in them. And I don't want to pull my motor out to check. But is that a possibility that they are the flat ones?

And thank you for that bit as I have not been able to find 16v performance cams. I understand I have to to get to cams and know it will be more but I'm looking more at the long term. Now I have come down from my original idea of 500+ hp and decided on a more realistic of ~300. But I want to stick NA and I figured if just swapping to 16v (increasing breath-ability) I will gain roughly 40 hp. And with the increase in breath-ability I will have also increased the efficiency of my 2.3l air pump.

Also what are the things the influence rpm powerband? I know advanced or retarded (lol retarded) timing can affect rpm. But there are still things I don't know

Quote
CaliMeatwagon

Quote
john vanlandingham
16v pistons and all B230 have dishes in them, and that hurts comp...

I don't want to argue with you as you have more experience but when I replaced my head gasket I think my pistons had flat tops (motor is 91 NA). I could be wrong but I really don't remember any dish in them. And I don't want to pull my motor out to check. But is that a possibility that they are the flat ones?

Not according to the piston manufacturer as far as I can recall. All North American B230s have some dish even if its jusr 2,2mm x 67

See if this works:
http://www.motorenteile.mahle.com/eLIZA/mahle/query/engine/byParams?cocoon-action-6a2326643a185b3e136a3e4201670972746e5935:EngineQueryResult:collapseObject&%2Fresult%2Fselector%2FnodePath=%2F12359%2FrelatedVehicles%2F12553#spa1810697485

Then click on the little icon to the right:


And there should be a chart like:
KH 39,7 stands for Kompression hochheit
MT 2,2 stands for 'mulde tief'----bowl deep (t=d and f=p, ie- ee)
AA 25
GL 64,7 is I believe gesamt lange---overall length.

Look around.. but in a way its moot point, the moptors are low comp, you want high 10s to mid 11:1

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
CaliMeatwagon
And thank you for that bit as I have not been able to find 16v performance cams.

Well it was the lack of suffciently large cores for putting lobes worth a damn that drove Lawrence to decide to make cores with big circles where we could make any crazy profiles..
I did the machining and saved him 2/3 of what he was set to pay, and still made good money on the job..

Here's some piccies from when I did them:




Now a cam like this can be done and reatain the stock geometrt and shim set:

Quote

I understand I have to to get to cams and know it will be more but I'm looking more at the long term. Now I have come down from my original idea of 500+ hp and decided on a more realistic of ~300.

Horse power isn't important above some point. If nobody is past 175 bhp in your class no point in doing 300. 210-225 is a huge advantage and doable, just worry about delivery. Broad, torquey delivery with power that can be put down..
Most guys in n.a. 2wd cars are under 130 bhp.

Quote

But I want to stick NA and I figured if just swapping to 16v (increasing breath-ability) I will gain roughly 40 hp. And with the increase in breath-ability I will have also increased the efficiency of my 2.3l air pump.

Just means it will flow more IF there is a demand to flow more, and without changing the demand, and the interplay between cam and compression creates the demand.

Quote

Also what are the things the influence rpm powerband? I know advanced or retarded (lol retarded) timing can affect rpm. But there are still things I don't know

The thing that creates the powerband is:

the shape of the cam lobe.... not merely timing and lift, but the shape.


There you can see a stock whatever emissions cam and a performance cam for rally, quicker and higher opening.
A quicker and bigger gulp of air.

See?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.