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Highest expected NA horsepower

Sleazy_E

Sleazy_E

New member
Joined
Oct 19, 2008
Location
Houston
What's the highest expected NA horsepower one can get out of a B21F? For example, once my car is up and running, I'd really like to have 180hp without a turbo. Being a newb to B engines... I'm not sure if that's a pipe dream.
(FWIW, I understand the concept of stroking and boring :oogle:).
 
You can get some pretty good hp but it does take good old green stuff in decent quantity to do it. Of course you can start with a larger engine of 2.3 displacement and have a bit more power from that alone. What is your plans for the engine? Do you want a fun daily driver or are you going to race/rally? That'll help with cam suggestions for example. But you are going to need headwork with valve train upgrades, raised compression, raised fuel pressure, higher flowing exhaust to go along with that uprated cam you are going to need.
 
vvpete said:
About 250 hp, which is what the Grp A cars get from an N/A

It's relatively easy to get 180 hp from a B12F using K-jet
Click to expand...

yeah no. grp a wasnt na, also 180 isnt easy from k jet. i stuck thousands into a na engine for a while. it takes money talk with krl on here. i ran 11:1 compression with webber dceo's and flattops i bet i maybe made 140 whp MAYBE.
 
2fast242gt said:
yeah no. grp a wasnt na, also 180 isnt easy from k jet. i stuck thousands into a na engine for a while. it takes money talk with krl on here. i ran 11:1 compression with webber dceo's and flattops i bet i maybe made 140 whp MAYBE.
Click to expand...


If you invest money wisely I think 180 flywheel is relatively cheap to achieve (but like you said, probanly not with kjet). Past that or past 200 it starts becoming quite-very expensive (vs a turbo).
I think 11.0:1 is not enough for a nice N/A engine as is running a K cam which really isn't anything special, but 140whp isn't that far from 180 flywheel/crank.

I think if you would have raised your CR to 12.0/12.5:1 and ran a descent cam you would have gotten 180 or probably a bit more, the K cam just isn't suited for a lot of power since it doesn't rev high enough. In my 740 the power noticably dropped past 6000 rpm.

People at savarturbo get slightly over 200HP from a good cam, high CR, 38/46mm valves, descent header-exhaust and carbs or a good tune.


Sleazy_E said:
What's the highest expected NA horsepower one can get out of a B21F? For example, once my car is up and running, I'd really like to have 180hp without a turbo. Being a newb to B engines... I'm not sure if that's a pipe dream.
(FWIW, I understand the concept of stroking and boring :oogle:).
Click to expand...

No offence but this is a dumb question (don't take it personal). How can people give you advice without knowing your budget, goals etc etc.
If you ask how much can a B21 produce with or without turbo, well the answer can be 75hp for a badly worn example or 1000hp for a Scandinavian monster which is severely modded.

People get 275-300HP from 8v N/A engines, 16v might get you somewhere North of 300hp. Getting that much power will cost a lot of $$$.

How can we tell you how much to expect without knowing which mods you will perform?
 
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vvpete said:
About 250 hp, which is what the Grp A cars get from an N/A

It's relatively easy to get 180 hp from a B12F using K-jet
Click to expand...


Sorry something MUST have gotten lost in translation....
GrpA REQUIRES original intake and exhaust manifolds as well as stock valve sizes and whatever the guy writing the Homologation forms dares to claim for production tolerances for the ports, and typical tolerance is +-0,8mm although I have Homologation papers here for my Saab showing +1,8/-0,8.
Until 1 Jan 1986 GpA mandated max cam lift as whatever max cam lift was stock.

And of course same fuel and ignition system.

Thus a claim of 250 bhp with all the stock restrictions and limitation is pretty obviously not going to happen.

Indeed we see some very expensive VOC motors---all with OEM parts but the ability to mix and match ideal parts and invariably 2,3 making what? 145 at the crank? Maybe.


In a free form class allowing whatever, BUT retaining OEM intake manifold we might possibly see 175.
 
2fast242gt said:
yeah no. grp a wasnt na, also 180 isnt easy from k jet. i stuck thousands into a na engine for a while. it takes money talk with krl on here. i ran 11:1 compression with webber dceo's and flattops i bet i maybe made 140 whp MAYBE.
Click to expand...

First understand that Group A was a GROUP of classes introduced at the same time as GpB and GroupN
GpA and GpN were a groups of classes for 4 place cars.
Both required minimum runs of 5000 identical cars ie an OEM had to make 5000 of the base GpN car aqnd that qualified them for GpA as well.
All three Groups had classes for 1300cc, 1600cc, 2000cc, 2500cc, and 3,0 and over.

EVERYBODY homologated their cars (submitted Identification papers where EVERY dimension, length, tooth count, weight, etc was identified and photographed.

So there were normal aspirated GpA 1600 cars---my own Saab 96 was rebuilt to GpA spec in late 1986 so i could enter Olympus World Championship Rally in December 1986. This involved making a NEAR STOCK 1,5 V4 (only compression ratio and camshaft were free to mod) and yanking out my big valve +3mm overbored 1700 V4 which was 1815cc------there were GpN 1300s and the GpB cars were mostly around 1700cc cause turbo cars had a 1,7 multiplier for engine voluume.

So of course there were GpA 2,1 normal aspirated Volvo 240s somewhere, but as it isn't the most optimal motor in stock form and it is a relatively heavy car, it never was popular except in classes that allowed engine mods and there is was at home.

Bur re: your car


What valve sizes did you use?
What camshaft did you use?
You should point out you had smallish---for a motor 2,3 liters---45 DCOEs which are more appropriate on motors for all round use around 1600-1800cc.

And seriously, how did you calculate your compression?

Cause you know that 2300s even with 45s can do outputs around 200-210 with the right bits.
 
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John V said:
What valve sizes did you use?
What camshaft did you use?
You should point out you had smallish---for a motor 2,3 liters---45 DCOEs which are more appropriate on motors for all round use around 1600-1800cc.

And seriously, how did you calculate your compression?

Cause you know that 2300s even with 45s can do outputs around 200-210 with the right bits.
Click to expand...

I think he used stock valves and a stock 531.

Some VOC cars get 145 WHP which isn't bad for what they have, at least over here. Since the Dutch rules are slightly different from the Swedish. IIRC they are allowed to port the head. Dutch VOS drivers aren't.

Just read a post about a b23/230 on savarturbo with 192 hp. Only few mods, folkrace cam, header, high CR, E85, 531 head and probaly some nice carbs.

John, I know this has been discussed to some extend but I would like to ask you again. For a N/A engine producing around 200-230 HP would you rather have carbs/throttle bodies or a large runner big plenum big tb intake?

Maybe not quite ontopic, I do wonder why Swedes get so much HP from Mikuni yamaha R1 40mm bike carbs? Seems they like them a lot, probably because they are a lot cheaper compared to 48/50mm automotive carbs.
 
Ruben said:
I think he used stock valves and a stock 531.

Some VOC cars get 145 WHP which isn't bad for what they have, at least over here. Since the Dutch rules are slightly different from the Swedish. IIRC they are allowed to port the head. Dutch VOS drivers aren't.

Just read a post about a b23/230 on savarturbo with 192 hp. Only few mods, folkrace cam, header, high CR, E85, 531 head and probaly some nice carbs.

John, I know this has been discussed to some extend but I would like to ask you again. For a N/A engine producing around 200-230 HP would you rather have carbs/throttle bodies or a large runner big plenum big tb intake?

Maybe not quite ontopic, I do wonder why Swedes get so much HP from Mikuni yamaha R1 40mm bike carbs? Seems they like them a lot, probably because they are a lot cheaper compared to 48/50mm automotive carbs.
Click to expand...


VOC is Sweden allows only clean up out to the "stock" dimensions.

And of course individual throttle bodies would be the choice.
Preferably 48 DCOEs with 40 or 42mm venturis.
Seems similar sized throttle bodies is the choice if budget allows.
 
With a 16v I'd be hoping to get a few ponies more than 180. Wouldn't be worth it imho to go 16v for only 180hp.
Would save some money in head work but a 16v head isn't cheap over here (prices vary from E50-E350 which is pretty common). Getting the conversion parts+ the head will cost just as much and probably more to get a 8v head/engine to 180hp.
 
Let's start a pool. See how long he lasts before he gives up and goes turbo. ;-):rofl:


Seriously, unless you are building to a certain racing class that mandates no forced induction allowed, turbo is about half the money for twice the power. Just something to consider. I'm not exaggerating. Welcome aboard!
:cheers:
 
I've got around 175 hp at the crank on the PV. It's hard to make much more torque with a given amount of displacement with N/A.

So first, get as much displacement as possible. B23 pistons, overbored block (you can do that with a B21 block, right? I've done it to a B18 before - to B20 sized pistons, and with 2 B20's - to B21 sized pistons). And/or get a stroker crank for another couple hundred cc's. Either a Penta crank, or an offset ground crank. With custom rods. No replacement for displacement.

Next, it's all about revs. Torque * RPM = HP, since torque is limited somewhat by the displacement, spinning faster is the only way to make more power. This is a holistic task - you need to improve the entire throughput of the engine at high RPM's. Rarely will there be one discrete bottleneck - you have to get everything to work together to make meaningful improvement. but the basics - air box, intake, port work, bigger valves, bigger cam (needs to be carefully selected to match your RPM range and the hardware it needs to work with), header, exhaust.

All in all, you hit various cost/benefit ceilings with N/A power tweaks. You can make lots of power, but at some point it becomes rocket science, and uses unobtanium parts. And in the end, you might get 200 HP, maybe even 225 (crank) out of a heavily tweaked N/A motor, which is about what a junkyard B230FT long block makes with about $500 in supporting mods. And the benefit of a B230FT J/Y long block is that if you blow it up, you haven't grnaded $$$$ in custom built parts, you just broke yet another $300 junkyard motor.
 
its an engine, cant be that hard to figure out.... just look at it and do what ya feel til it pops then do it again..

i have folks upset cause i went old school and cement filled a block to run alcohol. eh , what do i care what it makes.
 
Ruben said:
With a 16v I'd be hoping to get a few ponies more than 180. Wouldn't be worth it imho to go 16v for only 180hp.
Would save some money in head work but a 16v head isn't cheap over here (prices vary from E50-E350 which is pretty common). Getting the conversion parts+ the head will cost just as much and probably more to get a 8v head/engine to 180hp.
Click to expand...

He is in Huston, heads are fairly cheap and common. You cannot step foot in a machine shop for what it would cost to build a NA 16v b230. It would easily do 180hp with no drama. It would likely run more consistently than most of the ghetto +Ts around here.
 
so our ITB engine.

B23 10.8:1 compression stock intake, header, stock head and D-cam made 138rwho and 148rwtq

a 2.5l 16v engine we built a few years ago recently made 268rwhp

So I would say that our 138hp 2.3l stock engine is a baseline with 268 being the best we have seen to date on an NA volvo engine from our shop.
 
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