What engine spec to reach 75-85 bhp ...
Discussion
with lots of mid range torque for 1275cc
I drive lots of motorway work at slow speed, loads of city driving. never stable speed all way, just hard accerlating, and braking. its driven everyday use.
I got 1275 with Mini spares Small bore inlet(pretty rubbish), HIF38 carb+K&N filter, (got hif44 laying around) LCB, RC40 center exit singlebox. NGK sparks plug.
everything is pretty much standard
Should i get a metro inlet manifold, (how do you can tell if its metro manifold?)HIF44 carb on, mild head job, new 286 cam by recommation?
What else i should make to put out 75 - 85 bhp or higher as long standard gear box can cope.
Or am i being too silly with those hp figures?
I drive lots of motorway work at slow speed, loads of city driving. never stable speed all way, just hard accerlating, and braking. its driven everyday use.
I got 1275 with Mini spares Small bore inlet(pretty rubbish), HIF38 carb+K&N filter, (got hif44 laying around) LCB, RC40 center exit singlebox. NGK sparks plug.
everything is pretty much standard
Should i get a metro inlet manifold, (how do you can tell if its metro manifold?)HIF44 carb on, mild head job, new 286 cam by recommation?
What else i should make to put out 75 - 85 bhp or higher as long standard gear box can cope.
Or am i being too silly with those hp figures?
Will the 286 cam be too much for an around-town 1275? The 286 Scatter in my 1380 has not much bottom end.
Seeing as you've got the HIF44 it would be a shame not to use it.
That'd be your easiest first step.
Is the engine out currently?
Editted to add: Get hold of a copy of David Vizzard's 'Tuning the A-series engine' book. Then you'll never have to ask another question as all the answers are within.
>> Edited by Guy Humpage on Thursday 23 October 13:21
Seeing as you've got the HIF44 it would be a shame not to use it.
That'd be your easiest first step. Is the engine out currently?
Editted to add: Get hold of a copy of David Vizzard's 'Tuning the A-series engine' book. Then you'll never have to ask another question as all the answers are within.
>> Edited by Guy Humpage on Thursday 23 October 13:21
You are being very realistic. It's relatively easy to get to 80+ bhp and if I were doing this I would spec the engine as follows:
Metro GT or Megadyne 266 cam, gas flowed head with 37mm inlets and 30mm exhaust valves. 10.5 to 1 comp ratio, big-bore LCB with a Maniflow or RC40 1.75" exhaust system, HIF44 on a ported and flowed manifold (an after-market one is best, but a Metro GT one is OK). Lightened flywheel, but not too light. I am guessing you have a Verto assembly, so go for a bit of machining off of it. You don't need a steel one unless you want to go over 6700 rpm sustained (which your crank won't take anyway).
Time the cam in properly using offset Woodruff keys.
Fit an Aldon 'Yellow' distributor or equivalent. You will gain between 4 and 6 bhp by boring to +.060" to 1330cc.
If you build up the engine nicely you will get about 80 bhp from 1275cc or 85 from 1330cc and it will be very driveable. Optimim diff ratio for this configuration is probably a 3.2 with standard gear ratios or 3.76 with a s/c c/r box (which I would not advise for your use).
I recently built a 1275GT engine to approximately this spec, although we used a 276 cam, and at 1330cc it gave 86bhp at the flywheel on Peter Baldwin's rollers.
Just one thing - make sure you machine the deck of the block so that the pistons come right to the top. this optimises the 'squish effect'.
Who is going to build your engine? It needs to be someone who is fussy about measurements and settings, and that don't come cheap. You get what you pay for!
Email me for more advice if you wish.
Metro GT or Megadyne 266 cam, gas flowed head with 37mm inlets and 30mm exhaust valves. 10.5 to 1 comp ratio, big-bore LCB with a Maniflow or RC40 1.75" exhaust system, HIF44 on a ported and flowed manifold (an after-market one is best, but a Metro GT one is OK). Lightened flywheel, but not too light. I am guessing you have a Verto assembly, so go for a bit of machining off of it. You don't need a steel one unless you want to go over 6700 rpm sustained (which your crank won't take anyway).
Time the cam in properly using offset Woodruff keys.
Fit an Aldon 'Yellow' distributor or equivalent. You will gain between 4 and 6 bhp by boring to +.060" to 1330cc.
If you build up the engine nicely you will get about 80 bhp from 1275cc or 85 from 1330cc and it will be very driveable. Optimim diff ratio for this configuration is probably a 3.2 with standard gear ratios or 3.76 with a s/c c/r box (which I would not advise for your use).
I recently built a 1275GT engine to approximately this spec, although we used a 276 cam, and at 1330cc it gave 86bhp at the flywheel on Peter Baldwin's rollers.
Just one thing - make sure you machine the deck of the block so that the pistons come right to the top. this optimises the 'squish effect'.
Who is going to build your engine? It needs to be someone who is fussy about measurements and settings, and that don't come cheap. You get what you pay for!
Email me for more advice if you wish.
Basically as Cooperman says, you get what you pay for. Buying an off the shelf head and dizzy will never be as good as getting one made for you engine. Fit the HIFF 44 as you will undoubtedly be under carbing the Engine with the 38 this is only a 1"1/2 carb.
Aside from that it is time to take out the engine. A cam change to maybe 276, and a head job. But the head will be expensive.
Aside from that it is time to take out the engine. A cam change to maybe 276, and a head job. But the head will be expensive.
heh, I would put on HIF44 on, the Inlet mainfold i have doesnt have a hole for servo plug to put on
i need to Drill/tap that and smoothen it out.
the inlet mainfold is unknown type but it look good enough for job it have 44mm hole.
I cant take the engine out at the moment, and change the cam, head but will do though.
Ahh so much for poor student
Look like I have to buy a copy of dave vizard book. that name keep popping up.
Jay
Agree with Paul V...dyno after work is ESSENTIAL to see the fruits of your labour(s)...even if it only signing your name on the cheque...earmark £100 for this.
Everyone so far has overlooked the obvious...75-85 @ the wheels or flywheel !?!?...Makes a big difference.
I have driven a 649 on the road in a 1310...its tollerable if set up right re above....so IMHO generally aim high on cam spec and then if doubts creep in during build, time it in a 3-4 deg early (inc 2 to allow for chain wear), otherwise just the 1-2 deg early.
An 1 1/2 SU is good enough for the power u r looking for...again if set up OK...the best is a DCOE but the induction roar is NOT user friendly...and the hole in the dash kind of b*****s your car when it comes to resale unless to someone likeminded....1/2 way house is a downdraft but cash may rule that out !?!?
A decent head will get u some of the way there but to get 85 @ the flywheel, let alone the wheels would be somewhat abitious without a cam change...which means an engine out job...IMHO again...best is to build a whole eng/gbx on the bench @ leisure...then swop it over a w/e.
For an around town sprinter, a 3.9 diff is the DD's
...works out @ 94 mph @ 6000 with 1:1 drops & 12" wheels if I remeber rightly.
Email for further info if req'd.
G.
Everyone so far has overlooked the obvious...75-85 @ the wheels or flywheel !?!?...Makes a big difference.
I have driven a 649 on the road in a 1310...its tollerable if set up right re above....so IMHO generally aim high on cam spec and then if doubts creep in during build, time it in a 3-4 deg early (inc 2 to allow for chain wear), otherwise just the 1-2 deg early.
An 1 1/2 SU is good enough for the power u r looking for...again if set up OK...the best is a DCOE but the induction roar is NOT user friendly...and the hole in the dash kind of b*****s your car when it comes to resale unless to someone likeminded....1/2 way house is a downdraft but cash may rule that out !?!?
A decent head will get u some of the way there but to get 85 @ the flywheel, let alone the wheels would be somewhat abitious without a cam change...which means an engine out job...IMHO again...best is to build a whole eng/gbx on the bench @ leisure...then swop it over a w/e.
For an around town sprinter, a 3.9 diff is the DD's
...works out @ 94 mph @ 6000 with 1:1 drops & 12" wheels if I remeber rightly. Email for further info if req'd.
G.
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