not enough power on throttle bodies!

[rysmee]

ok, so i've just got my 1.6 8v back on the road after getting throttle bodies and omex management of bernie at nova tech.
Fitted all my self and every thing seems to be working as it should.
i have a map which bernie gave me that was on a similar engine set up, and have taken it to bernies to get them balenced etc etc, but i have not rolling roaded it yet.
the problem is.. ITS SLOWER THAN BEFORE !!! (when i just had refurb-ed bottom end, B++ head and cam etc).
How can this be???!!! surely there cant be that much fine tuning to release another 20-30 hp which is what they should have given.
before u say, how do u know its slower? it is definately slower as i have points on roads where i know what speed i can get to.
eg of how bad it is: normal speed at sign after roundabout:95
NOW barely 80!!!!!
whats going on???? please someone help me.. have i spent ?1700 for nothing??!!

[Stuart]

get it setup at a rolling road so its mapped correctly, then have the map tweeked on the road (as that makes even more difference)

[Jim]

Not saying it's your fault, but get them to check your installation to see if you have miss-fitted anything.

It should all work out in the end though. Would be intresting to see how a 1.6 8v on tb's will compare to a similar engine on carbs.

Jim

[peester]

get some pics/specs up mate; let us know how u get on; im planning on doing this too. though im really sure you will get good gain. you'll be prob only the second person to do this ya know.
you had jenveys? has the bottom end had a recon?

[Aragorn]

i'd expect the throttles to produce slightly more power - maybe 5-10bhp due to the very high accuracy of the fuel and ignition settings along with the efficiency of fuel injection over carbs

[mikeoxford]

i await to be stood corrected. :!:

but dicko wasnt having very good results from his TBs and was having trouble keeping up with lesser power cars.

his just needed a good dyno etc

*stands to be corrected*

and once it was done i think it put a smile on his face :lol:

[so1o]

I have been doing a lot of reserach on tb's lately, and getting them mapped properly does pay, can be expensive but well worth it in the end.

Take Jims advice first, always good to check everything is ok. Very easy to have missed something out or whatnot.

Solo

[rysmee]

ok cheers guys. i'm not gonna drive it untill i can get it on the rr, just feels like its damaging it!
will put pics on here as soon as its a sunny day and can get some decent ones!

[MC]

The first time most people use TB's they are dissapointed.

Further mapping will help, but most of the performance will already be there.
The problem with TB?s is their size. In carbs, the bigger the choke size, the more peak bhp you get, and the higher it is up the rev range, and as a direct result, the less low end torque you have. You might get a greater volume of air passing through the carb, but it is slower and doesn?t accelerate as quickly, and at the start of the cycle the the cylinder wont fill as quickly. a tuned 1.6 8v on carbs typically would run 32mm chokes. 34mm chokes would be a little large and would make the car slightly peaky, and any larger will result in loss of driveability. TB?s tend to be around 40mm in diameter, so you can see the pattern.

Now all is not lost, the bhp is there, just much higher up the rev range, and you have to drive it hard and keep the revs up or you wont go anywhere. Typically the engine will come on song above 6k rpm and reach peak power??.you may never know. CP?s engine is around 170 bhp at 7,500rpm, and the bhp is still climbing when it hits the rev limiter, in fact is climbing faster than ever. A lot will then be dependent on how high you will rev your engine, you?ll need to rev to at least 8k rpm to make the most of it, and no amount of mapping will bring the peak power lower down the rpm, only get it spot on. You may need to concider ARP bolts to give peace of mind at those rpm?s

Best fine tuning will be done on the road.

Whoever sold you the throttle bodies, should have explained this.

MC

[rysmee]

yeah i failed to mention that....
it feels like its missfiring/running on three untill about 3500/4000 rpm then it really kicks in, and keeps pulling all the way up to the limiter, so i guess the power is there, just in a different place to what im used to.
i already have arp rod bolts so no problem there with a little higher revs.

[rysmee]

pics on now so take a look, i'm quite happy with the result.

still havent got it on the r/r, waiting for bernie to have some time.

MC (or anyone): will changing the cam move the power band into a different place(lower) or is it just the design of the boddies that mean the power is always high up?

[Will]

that is one smart looking bit of kit mate, very impressive!!!

qn: you have removed the washer bottle? so if ur windscreen gets dirty tough shit? or is it relocated?

[Dpnova]

The engine looks great along with the rest of the car.

[SKoob]

your nova looks awesome m8, also its good to see someone tuning the 1.6 lump to its full potential :+:

[S_Gault]

MC has the point..

theres is no venturi in a throttle body, but Id also say that youve lost out in the mapping.

The throttle body engine should make more torque than the carb one due to better control. (ive done several).

If you want to send me the map, I'll have a look at it. What system are you using.. Ive mapped MBE, emerald, DTA, Luminition, Motec, GEMS and Perfect power in past.

I ve also made up some chokes before for throttle bodies to speed up the gasflow. For engines under 2.0L, I now use a taper throttle body or make my own from old carbs.

Steven

[rysmee]

thanks S_gault, i'll get the map off my laptop tonight and mail it, i'm running omex management. i heard mixed reviews about them but bernie at nova tech said it would be fine for my usage, and wasn't too expensive.

Will: i did have the wahser bottle under the scuttle but the bottle i picked up from the scrappy leaked so i took it out and thought sod it, dont need a washer bottle anyway! i'll just put it back in its origional postition for mot.

[MC]

I agree that you might get more torque than carbs when mapped properly, and this is where the relationship between torque and bhp gets confusing. CP's torque and bhp climbs all the way to the limiter, having morte of both than most, and if you drive it correctly all is fine, but to a novice who is not used to the characteristics of engine tuning, then it will always feel less torquey low down, there is no way you can have more low down grunt on 40mm TB's unless you do make chokes for them.

To add on from the mapping, once it is complete on the rolling road, don't just settle for that, get a copy of the software and use a laptop, and record some logs. Use this information to fine tune the gaps. You might not make more peak power, but you will smooth out the driveability. If in doubt, ask someone who has done it, and don't touch the ignition, leave that to the experts.

MC

[peester]

pics on now so take a look, i'm quite happy with the result.



where mate?

[rysmee]

ah.. my stupid g friend thought it'd be funny to put a stupid pic of me with my car, and now its gone for verification, so thats why they are not there, even though i've deleted the pic.
women eh!! her lead was obviously too long.
never tell em ur password!

[CP]

IMO to get the best out of small TB'd engines you need to think about gearing. Ideally you need a comp. close ratio box to make sure when you get in to the high revs you stay there. Its all out performance tuning with little compromise to get the potential from your TB's.