More power needed!

[baybus70]

I run a 71 bus with a 1776 Lawrie Petit engine.
It has twin 40's external oil filter etc.

Only problem is i find it a little short on power. It will max out on the motorway at 75mph,it will not give any more! It does take a while to get to this point tho! Hills are a problem too, it really struggles!
Should i be concerned about this for the size and power of engine or is this about right.Could it be the gearbox?
It doesn't have a lot of interior in and only a small Danbury pop top. I'm 12 stone so it aint me!
Thanks in advance! 8)

 

[Guest]

gearbox will limit your max speed and how quick you get there but its about torque through the range as well. I would have thought a 1776 would be sufficient to pull up the hills especially with twin 40s, i would look at a tuning/rolling road session first.

i dont know about you but 75 would be more than fast enough top end for me on any road in a Bay

 

[Joval]

What's your daily?

 

[baybus70]

What's your daily?

Daily is an Audi a4 1.8

Maybe it's just me but i have had more than 10 other air cooled vw's,including a '68 bus and none of them seemed to struggle with hills quite as much!

 

[Tofufi]

When was it last serviced?

My '71, when running spot on will do 80 absolutely flat out on flat ground. Takes a while to get there though.

Maybe it is the extra 1.5 stone lighter I am :lol: (actually, my van had a weeks worth of camping stuff for 6 people in it then!)

Since then, I've never dared take it above 65 again 8)

 

[Joval]

Mine's the same - 1600 feels under-powered on long hills, but it's my first type2 so I've nothing to compare it to.
(daily is a Golf Tdi, last dub was an 1835cc oval) :mrgreen:

 

[baybus70]

Serviced under a week ago!
Last air cooled was a 1641 gt beetle. It flew.
Is there any benefit from fitting the GT box, maybe that would do it?

 

[froggy]

Get used to life in the slow lane!
It felt wierd the 1st time a lorry slip streamed me, but know i just sit behind them and let them drag me along

 

[Tofufi]

Serviced under a week ago!
Last air cooled was a 1641 gt beetle. It flew.
Is there any benefit from fitting the GT box, maybe that would do it?

That would make the acceleration slightly slower, and probabl worse up hills.

It is hard to say if your engine even has a problem, to be honest. The GT box will give longer gear ratios. I don't think it is a straight swap.

 

[baybus70]

I think i'll get it dyno'd and see.
Maybe it's just me as i haven't driven it in 11 months, and in that time have owned a V6 Passat,MK1 GTi and an now an A4.

I think i've just been spoilt!
Thanks for all of your suggestions tho.

Anyone know what approx BHP a 1776 with twin 40's should kick out? Just intrested!

 

[Joval]

Depends on the cam and heads - 80 - 100 ish

 

[easy]

definately something up there :?:

You should be getting around 90bhp from that and with twin 40s you should get there pretty quick aswell. Make of 75 on a standard box is wrong as I have a standard gearbox with a 1600 engine and twin 34icts and mine does up to 86mph (this is on the dyno, so correct).

I would try and work out what gearbox you have and then go for a dyno as something is afoot for sure. :wink:

 

[james_stan]

definately something up there :?:

You should be getting around 90bhp from that and with twin 40s you should get there pretty quick aswell. Make of 75 on a standard box is wrong as I have a standard gearbox with a 1600 engine and twin 34icts and mine does up to 86mph (this is on the dyno, so correct).
:wink:

86 mph in a bus ! But on a dyno right so no wind resistance, or is that compensated for ? How high does that rev ?
Also 90 BHP seems a lot, practically double stock power. I'd have thought you'd need some pretty fancy heads, cam and exhaust as well as fat carbs to make that output ona 1776. But hey what do I know.. A dyno/tuning session at an aircooled specialist will reveal all no doubt.

James

 

[slowboy]

I've also got a Laurrie Pettit 1776 in my IRSd splitty van, fitted with weber34s and mated to a 1302s gearbox. It seems to give pretty good torque (stock heads and cam) and will sit all day at 70mph at 3200rpm and will go off the clock without too much hassle. I'm not too familiar with bay window performance yet (I'm selling the splitty to fund an early bay) but surely your engine should give you more performance than that. When it's struggling on hills could the engine be getting hot and losing power? Maybe the brakes could be binding also.

 

[baybus70]

could be losing power,one thing i forgot to mention.The PO put a stock exhaust on, will this limit power or be restrictive a little?
I do plan to change it as i know it's not the correct combo!

Here's a shot of the motor before the van was restored!Forgot what the red bull cans enclosing and what effect the gas flow jobby has.Somebody also said yesterday that they don't look like twin 40's.Hmmm

 

[easy]

definately something up there :?:

You should be getting around 90bhp from that and with twin 40s you should get there pretty quick aswell. Make of 75 on a standard box is wrong as I have a standard gearbox with a 1600 engine and twin 34icts and mine does up to 86mph (this is on the dyno, so correct).
:wink:

86 mph in a bus ! But on a dyno right so no wind resistance, or is that compensated for ? How high does that rev ?
Also 90 BHP seems a lot, practically double stock power. I'd have thought you'd need some pretty fancy heads, cam and exhaust as well as fat carbs to make that output on a 1776. But hey what do I know.. A dyno/tuning session at an aircooled specialist will reveal all no doubt.

James

It depends on tyre and wheel size aswell dont forget :wink: i have massive tyres 205 70 15s so will get a higher top speed than smaller tyres and wheels. You dont need fancy heads either, just qood quality ones (ported and polished also helps. I have a JK stainless exhaust which is better than stock, so gives a couple mores horses 8) My testing was on a lambo dyno (used for top spec racing/rally cars) and was calibrated before my session.

Your exhaust does hinder power if to small, i would change from a stock exhaust to something larger for sure. Not sure on your carbs, but you should check the filters as these could restrict airflow aswell as the chokes in the carbs maybe incorrect for the engine / carbs etc so maybe worth a check.

Im building a 1776 for my notch, with twin 40 idfs, everything ported and polished, straight cut gears etc and will be looking at over 90bhp even with the restriction of the shorter manifolds for a type 3 :mrgreen:

 

[Guest]

could be losing power,one thing i forgot to mention.The PO put a stock exhaust on, will this limit power or be restrictive a little?
I do plan to change it as i know it's not the correct combo!

Here's a shot of the motor before the van was restored!Forgot what the red bull cans enclosing and what effect the gas flow jobby has.Somebody also said yesterday that they don't look like twin 40's.Hmmm

the pic is a dead link for me :|

 

[baybus70]

Oh, sorry, have been movin some photobucket albums around!It's there now... :wink:

 

[AndrewHS]

When my '67 panel van was in daily use, only three years ago, we used to take it as 'tender' in convoy with the classic cars on our trips to LeMans. Fully loaded with tents, generator, fridge, and any thing else we could cram into it, it would max out at 82mph when the rev limiter cut in. I thought it was actually doing 75 according to the speedo, but was assured by those in the following car that it was 82. This is with a stock 1600, single port, standard (stainless) exhaust system. Who needs tuning mods? :lol: (It did take a while to build to it though!). I am doing something to improve the brakes. (see my query in technical forum).

 

[angus]

82mph!!!! :shock: - blimey!!