RedMist

I've just purchased a Jimco offroad race car with a B18C VTEC (sleeved down to 1650cc) in it's middle. I'm looking to up the ante and enter the new offroad racing class for 2ltr turbo's. I wondered if I should consider running a Honda B18C (or B18 with VTEC head) bored to 2ltrs and run turbo it. Consideration being I need a good spread of torque, good power, and quick throttle response.
Or if I should consider something like a Evo replacement?

W!d3b0dYr3X

If ur looking for torque its would be better to go with a b18. Nothin bad about vtec but they generally don't put down as much torque. Vtec= virtually torqueless economy cars. And an evo replacement? Well being one that owns both a honda and an evo I say if u got the dough then u won't regret it. The evo matches all of ur needs massive torque all at around 3600 rpm great power, very balanced and good response. Full boost hits around 3500 on a stock turbo and with upgrades u can make great power. Their are plenty of 1000hp+ evos so getting power and torque from the 4g motor is so easy a caveman can do it.

wantboost

iTrader: (2)

you clearly didnt read the thread you tool...

i'll type a meaningful reply when I have time tonight

Garage 808 Hatch

You already have the Honda motor. Might as well just bore it out to 84 or 85mm and use it. Seems to be the most cost effective route IMO. What kind of power and tq are you trying to achieve? Properly sizing the turbo will be the biggest deciding factor for the broadness of the powerband

RedMist

Thanks Gentlemen,

It's a Danzio race engine, was thinking of selling on the all race engine and replacing it with another sleeved, high flow, turbo block and head. The reason to go Honda is to minimise costs with replacement of the M4 Motec, a new CWP for the Fortin sequential, engine mounts, etc.
My current Jimco has an expensive Cosworth/Nissan V6 twin turbo in it's belly. But I'm keen on reducing costs, hence the 2 ltr option. With the 6 speed sequential I should also be able to gear it sufficiently to get reasonable torque at the wheels and get a good portion of the Cosworth performance.
With a reasonable flowing 2ltr Honda I would hope to match the Mitsi. I do understand the issues with turbo matching and was thinking BW EFR 7064

hybrdthry911

You clearly have no clue what you're talking about. Might be best not to give other people advice. VTEC cars just make a **** load more power with the same torque because the engines breathe better at higher rpm's. LS motors only make more torque because they suck at making power in the higher rpms. Higher torque is just a byproduct of pushing the turbo setups harder to achieve the same power, not because they are "torque monsters".

Spawne32

iTrader: (3)

LOL you probably should explain that its because of the fact that the b18a/b has a longer stroke then the b18c or most other vtec engines, they have to sacrifice some low end torque through the stroke for higher RPM stability.

W!d3b0dYr3X

I don't know what im talking about? Its an opinion with evidence to back it up. A b18b1 puts down 140bhp@6300rpm and 121ft/lb@5200 whereas a b18c puts down 170bhp@7600rpm and 128ft/lb@5200. Now let's compare. The c makes only 8 more ft lbs at the same rpm and 30 more bhp 1300rpm higher than the b18b1. Now imagine if u could see the b18c at 6300rpm it would probably not have much more power than the b18b1. Torque is rotational force. Torque is the pull of the car and what makes it move. The op said in his post he is looking for good response and midrange power. Looks to me like the b1 fits the bill better than a vtec so ya I do know what I was talking about. Want midrange b18b1 non vtec want uptop power a vtec prob do better.

RedMist

If anything I'd much prefer to rev the engine through. Shorter stroke.
I can't see how VTEC can't be beneficial. The VVT on my Nissan has been instrumental in spooling the turbo's incredibly quickly. I was hoping to create the same effect using VTEC on the Honda turbo.
I'm aiming for around the 500hp mark with as much torque and spread as possible.

W!d3b0dYr3X

Another thing is the comment about pushing our turbos harder on non vtec apps to make up is not true there's dyno sheets and its been proven time and time again non vtec with similiar setups as vtec counterparts will gain more torque when turbocharged at the same level of boost. A quick google search on turboing a b18b will provide plenty of results that its one of the best to turbocharge because of torque gains and the motors ability to handle boost.

RedMist

Torque is a function of Power. You're misproving your own point. Using your information the B18C has more torque and a broader spread.
Turbo's also respond to flow more than anything else. It would seem weird that a smaller bore would hold bigger valves than one with a larger combustion chamber.

Spawne32

iTrader: (3)

Look, im gona put this a simple as I possibly can. Dont expect to make torque a Honda motor in general, they dont, its just how it is.

That being said, you want to try to build something that has more torque that all the other honda motors, you need to look at several things...

compression ratio
stroke length
bore size

and last but not least, your turbo specs

your compression ratio will give you a world of difference in low end response, higher compression, more response, lower compression, more boost required to get the engine moving, while compression may limit you with your maximum amount of boost, if you find the proper balance you will be ok.

the stroke length is one of the key determinations in torque output and where it is applied on the power band, yes, you can make 300 ft lbs of torque on a b18c5 @ 6500 rpm, but you need to make 500hp @ 9500 rpm's for that to happen. B18B's, B20B's (strictly speaking b series) benefit from a longer stroke from the factory, pushing the power band lower then vtec motors right from the factory, but they are limited in RPM's by the rod to stroke ratio, as at higher rpm's the balance of the engine increases the load on the cylinder walls and crank.

your bore size is your decision, I can tell you that you will not make an exceptional amount of torque a 1.8 liter motor, good luck with that.

turbo selection is not something i excel in so i wont make any suggestions, but spool up time, how much cfm it flows, how much boost it can make, all play an important factory in where the power is made and how much, reading turbo efficiency maps is something i never could quite wrap my head around.


all that being said if you really want to make "torque" you might want to take a look at brian crower or eagle stroker kits, but again, this limits your high rpm's because this changes the rod stroke ratio to something radical, but pushes your rpm band lower and your torque higher.

Spawne32

iTrader: (3)

and to answer your question, yes bore it to 2.0, increase the compression ratio slightly

W!d3b0dYr3X

Ur sadly mistaken. Horsepower is a function of torque. Horsepower=torque*rpm/5252. Like I said torque is rotational force it makes a car move by rotating the wheels. If it was a byproduct of horsepower the car wouldn move u have to have torque to make the car even move and then u can get horsepower. That's common sense.

Spawne32

iTrader: (3)

RedMist

If I'm going to break the 2ltr limit I'm not going to keep the Honda. It's considerably easier to throw the 800hp Cosworth/Nissan in it's middle.
I don't understand the need to go even more undersquare than the standard. In all honesty I don't understand how Honda engines rev so high given their undersquare status.
Are you sure that B18a/b engines aren't making more power simply because they have the ability to have a greater capacity than the b18c?
Surely having a larger valve area must be beneficial to BSFC and also flow to spool a turbo.

RedMist

Do you even believe what you write?

Basic algebra.
If HP is a function of torque. Torque is also a function of HP.
hp=torque*rpm/5252
torque=hp*5252/rpm

That's common sense.

I'm fully aware of what torque is. I'm also fully aware that it's also a poor measure of performance. I use wheel torque as a function of the area under a dyno curve, in each geared ratio RPM range to give a true perspective on what an engine will do. However when attempting to explain offroad racing requirements, torque, which is often used by laymans to describe low end HP is the easiest way to describe it.

RedMist

I'd agree regarding the CR, it's certainly very important for spool. However it's a hard line to push as increasing CR means a reduction in boost. The current engine is running 12.5:1CR, way to high to run boost through it.
The plan at current is to run the bore out to 84.5mm (as I believe this to be a safe turbo limit) which will give me 1957cc and run the CR around 9 to 9.5:1. I'm hoping to build this engine to put a maximum of 25 psi through it on either E85 or VP112

DCtooD

Stroker maybe?

https://honda-tech.com/forums/forced-induction-16/built-gsr-17psi-355hp-375tq-2898882/

RedMist

Limited by 2ltr to stay in class.
It's also a very small turbo, and I understand why it ran out of "puff" I ran two 2860rs on my Nissan 3.5ltr engine before switching to Cosworth internals and a pair of GT2871'r (which are still too small). The turbo is choking that engine... severely. I don't know why he revved it to 7500 with max power made at 5250rpm.
It's also a very narrow spread of torque. Although the curve looks good, without holes, max hp and max torque are very close with dropoffs either side. You would have to work the gearbox hard to make the engine work.

This is what BW matchbot is predicting on a 7064. I'd be very happy if I can achieve it.

Required Inputs #1 #2 #3 #4 #5 #6

Engine Speed rpm 2000 3000 4000 5000 6000 7500
Engine Torque lb-ft 187.67 219.42 344.16 372.45 371.91 350.14
Engine Power Hp 105.9 184.3 311.5 427.6 491.2 518.8

96 GSR-T

There are some very funny comments in here.

For your 2.0L goal, I would do a Sleeved GSR or ITR Block with an LS Crank, with an 84mm Bore that puts you right around 1.97L. You will have the extra low end "torque" associated with the extra stroke and the top end of the VTEC head. This combo will have no issue reving to 10k and if you have enough compressor it should make power up there as well given everything else is up to par. Another combo would be an 85x87 straight GSR.

As already stated, the biggest thing that is going to affect your powerband is the Turbo Setup and Head Flow/Int Manifold. What kind of fuel are you allowed to run in this class?

Whoever said the straight LS would be a better match and keeps trying to justify why should have his sperm tube clipped. TQ in a FWD car is your enemy, especially when it comes in low and hard and your trying to apply it to the pavement with your tires not pointed straight or coming out of a corner.

Spawne32

iTrader: (3)

hybrdthry911

so by what you just said the b18c makes more torque at the same rpm as the non vtec engine, and just holds it out higher so you agree with me. You also do realize that with a higher revving engine you can gear it down to multiply torque more right? so if you geared them to top out each gear at the same then the b18b would have to make the equivalent of 145 ftlbs to match the actual torque output of the b18c. this only furthers my point of the higher torque of the non-vtec engine is merely and illusion for idiots. you preach about how cars don't move without torque, but how quickly you forget that torque without rpm's means the car goes nowhere either.

hybrdthry911

besides 2 liters what other restrictions are in the class? is the turbo size limited?

W!d3b0dYr3X

I can see where ur coming from cause I use to think the same so ill explain it better. Power or horsepower is amount of work done in a certain amount of time. U and I are changing a flat tire and it takes 200 ft lbs of torque to turn the lug nut and it reamins a constant 200 ft lbs. U take 10 minutes to get that lug nut off where as I take 5. That would equal up to u having one horsepower and I have 2. Now let's go back a second let's say u couldn't move the lug nut at all you put 150 ft. Lbs of torque on it and it doesn move. Guess what? U still exerted torque but u didn do any work so that explains how torque is required to produce horsepower which is what I was saying in the first place.a quick google search of torque vs horsepower pops up numerous articles. Yes horsepower is a function of torque in simple algebra terms, however its not algebra its physics that matters. Horsepower= work over a certain amount of time therefore it is a function of
torque. Without torque wheels would never move therefore work is not being done therefore ur precious dyno would remain at 0 peak torque and 0 peak horsepower. So yes I do fully believe what I write cause simple research yields results. If ur hell bent on keeping a honda motor and ur limited to 2 liters y would u bore the b18? Y not opt for a b20 with the 84.5 bore u are considering doing to the b18? U wouldn be sacrificing strength of the block if ur planning on running turbo? That's what I would consider doing but then again im stupid and don't know what the hell im talking about according to u