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1641, what carbs, what crank, what heads? This is Exhausting!

43K views 73 replies 17 participants last post by  jimbo198966 
#1 · (Edited)
Hey guys,

I'm building a 1641 engine, with Engle 110 cam, straight cut cam gear, (not sure which crank to get) 1.5 deep sump, not sure what heads or carbs to get either 34 ICT's or 36 DRLA's.
All I know is I am 18, I’m on a budget, and I want to make my 72 bug faster.
I was thinking of changing the crank because I want it to rev further to 6k or 7k safely, any good cranks for a good price?
The heads: - Lots of people have told me this is where the power lies, and the best thing to do is to keep my 1300tp heads and port them. Other people say get big valve heads.
Again, what’s the cheapest, most powerfull option?
And the carbs, people have told me how good 34 ICT's are and how good 36 DRLA's are. I still want to maintain a fair MPG but I just want power.
I guess merged headers are the way forward for grunt, but what back box is the best for performance.

If you guys could help me build a shopping list of parts to make a hot 1641 motor that’s achievable to save for, I’d be grateful.

Thanks guys
Marc
 
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#13 ·
The first part I agree with as it will provide a range of well tried options.

The second part has the right sentiment if a little tactless and discouraging.

Marc, I would suggest that you discuss the principle of modifying your bug beyond a standard 1600tp with your insurer as I think you might be in for a surprise! Different cams, multiple carbs will be very heavily penalised. Its not that what you propose is outrageous its that anything out of the ordinary that causes them more work will attract a premium. Remember the basic law of supply and demand is that your in the minority with a high demand and the insurer would rather not have your business (too risky copared with the 45 year old housewife with the Renault Clio down the road). If after the discussion with the insurer you have comfort that you can afford it then you will find the rest of us very helpful.

(there are ways and means of 'improving' a car within the confines of a standard car that ought not to attract any consideration - i.e. porting on standard heads, rejetting carbs, maximising the flow potential within the existing casting. Think of what a racer can do with the standard stuff in a very basic production formula.)

evilC
 
#4 ·
No it's not a younger driver issue, it's the spec of your engine. A 1641 engine using largely stock parts with give you a considerable improvement in power and performance and will also give you good economy which will help your budget. We built a 1641 using a 1300 donor case, stock crank and flywheel, stock cam, used stock 1600 T/P heads. Our one luxury was a a pair of Dellorto FRD34's which when married to an SVDA distributor manages to shove a '68 Westy Bay up hill and down dale with no effort and returns 31mpg on a run. So stick that lot in a Bug and it should fly.
 
#8 ·
Why would you want rev an engine to 6000 rpm that anyway. What you will have is a hi-torque engine that does not need to be revved to destruction to make it go. It's not a 2007 16 valve twin cam engine that develops no low down torque. The VW engine develops it's torque low down which gives good acceleration.
 
#9 ·
ive got a 1641, balanced bottom end (not counterweight), 110 cam, magnum straight cuts, full flow, murged header. its quite nippy, fun to drive. add a nice pair of baby dells to that and a mild port job it should be very nice. if you want to rev really high you will need a counterweight crank, a wilder cam, decent port and polish job. higher lift cams also require HD springs. having said that for a daily driver ive hear its not great to ahve a wild cam as it is lumpy low revs - but i have no experience of this.

decide on your buget. buy the best you can afford. have your parts balanced to improve longevity and youl have a ncie reliable nippy motor.
 
#10 ·
i just guessed that more rpm's i have the better. i dont scream my engines just like to know that it can take the extra grunt. I've heard storys about vw cranks bending/braking with anything over 5. and i cruise with a 1300 box so rpms are always applying to me on the motorway. if u suggest keeping my stock crank, then so be it
 
#12 ·
Go here for a guide on crank and bore sizes. http://www.johnmaherracing.co.uk/faq.htm#faq2

Also while you're there, have a read through whats on the site...can be very helpful.

Ohh...and ignore people if they patronise you. People seem to forget they knew fook all at one stage, so ask as many questions as you like, its the only way you'll find things out.

Good luck dude.
 
#15 ·
i've built quite a few 1641/Engle 110/ported stock 040 head motors, and it's a great combo. You can use a stock crank and rods, but get them balanced if you're planning some stop-light action! Also consider having the crank/flywheel drilled for 8-dowel location... it can only help if you have a lead foot!
if mpg is a concern, leave the heads alone and stick to ICTs or similar. however, if performance is required, you'll certainly notice the difference with the IDFs... and ported heads will make a big difference at higher rpm's, too.
Check out issue 1 of Ultra VW (still available as a back issue order at www.ultravw.com ) for the lowdown on porting your own factory heads for maximum velocity at all rpm, and be sure to pick a good quality 1 3/8 exhaust to go with your 36IDFs - you'll be surprised just how perky a well-matched mouse motor can be!
 
#16 ·
I've got a 1641 with balanced bottom end, 110 cam and 34 Webers and it makes about 80bhp at the flywheel. Heads are standard but the performance is adequate for the rest of the car.

It's got enough muscle to accelerate in traffic or on the motorway and with the 1500 gearbox it's flat out at just under 100mph. 0-60 is about 10 seconds.

I've got an EMPI exhaust on mine which uses the standard tailpipe holes on the apron and is quiet enough until you hoof it when it gives out a good roar.

7000 revs is too high unless you use a very strong crankshaft and even then you might need a new case because the bearings might not have enough support. If you make peak power at 5000rpm (like mine does) then you're changing up just after that.

Budget for a full flow oil system with filter while you've got things apart.

Uprate the brakes, suspension and don't drive like a tit or you'll kill yourself ;)
 
#17 ·
Thx for the heads up guys, and yeah, i think i'm gonna keep a good eye out for some 36's, port the heads my self, 110 with straightcut cam gear, balanced bottom end, lightend flywheel, 1 3/8 merged with a vwspeedshop phatboy type exhaust. shud work well no?
 
#20 · (Edited)
i would drop the 1641 barrels and just use good stock 1600 ones if your wanting the engine to last... 1641 barrels are just bored out 1600 ones and have thinner cylinder walls - whilst lots of these engines are in use with no problems, there can be cases of warping. at the end of the day its only an extra 50cc, i'd rather have peace of mind.

running high ratio lifters (1.25:1) and a mild performance cam (w100) is a good combo as it will give significant power gains and minimise strain on the valvetrain - high lift cams put a lot of force on the lifters and can be quite savage.

a well balanced stock crank will be fine for cruising at higher RPM, if your worried about accidentally over revving the engine, rev limiting dizzy rotor arms are available. its a good idea to dynamically balance the whole crank assembly - this takes the crank with the pulley, flywheel and clutch and balances the whole lot together and gives the best results.

cylinder heads are the key to making power - a bit of port work and polishing the stock heads will give you some extra power.

dont over rule kadron carbs, people think they are thirsty but they give really good BHP per £££, better than weber ICTs. kads can be drilled to work with the stock vac advance dizzy (which has the correct advance curve for the VW engine, unlike the 009) and will give very good mpg... see: http://www.lowbugget.com/main_page.html
 
#21 ·
on a mission sums it up-i would have thought engle 100 cam would be better for 1641? arguably better than scat c25 but a little bit more wedge.
as for carbs, personal preference, but again weber 34ict's would suffice with engine size....
oil flow system a good move -cb performance requires no work...
petronix ignitor a good investment.
engines are money pits and it is where you want to draw the line really. you will only really get proper performance from 1776 upwards but that is when prices spiral. you could bin the whole lot and just get a good mexican 1600!!
 
#23 ·
Why is that funny? A good stock brand new factory 1600, with a decent ignition system,a pair of good carbs and a decent exhaust should give you enough power to shove a bug along nicely and be uber reliable. I've got a mild 1641 with a pair of Dells and a 4 into 1 exhaust. But I'm 33 with 100% NCB and a clean licence that I have held for 16 years, so I am a good insurance risk. If you do decide to build a hot 1641, please do remember the most important upgrade of all, the brakes.
 
#24 ·
I spent ages on the heads of my 1641 and it made a vast difference. I carefully ground out the inlet and outlet points to ensure of no high spots, then took a couple of days to polish the metal to the max. Smoooth flow. That with 1.25 lifters. Which was nice!
 
#25 ·
I spent ages on the heads of my 1641 and it made a vast difference. I carefully ground out the inlet and outlet points to ensure of no high spots, then took a couple of days to polish the metal to the max. Smoooth flow. That with 1.25 lifters. Which was nice!
 
#26 ·
yanz89-i assumed this post was there for YOU to obtain advice.??if you ask any reputable company i.e terrys beetle services, t2d etc i bet they would say the same ref mexican 1600. they are reliable and reasonably priced, hence as an 18yr old with little cash and insurance to consider, then it is an option.
 
#29 ·
i just thought mexican engines were shite, i guess i'm wrong with that one. THo i did here summat abut Mexican Heads cracking.

Yeah i will be making a hot 1641, and i'm gonna get some dropped disc spindels, hurst line lock and a 2 inch beam cut to keep the wheels tucked in.

So here the list so far

Either 1585 or 1641 b&p's
Engle 110 with Straight Cut Cam Gear
1.1:25 Ratio Rockers
Twin Dellorto 36 DRLA's with Hex Linkage
Stock Heads with port and polish job and possibly a 3 angle valve job
1 3/8 Merged Header with a TurboThomas
Lightend FlyWheel
New Clutch
New Engine Mounts
1.5 Deep Sump

I change my oil quite frequently (every 2000 miles) so is it really worth taking everything apart to tap it for oil flow?

I guess i'll need a better breather system?
 
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