Boost limit / k series
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hi its not an a series or mini but a k series I have and this site is fantastic for info ( wish i had the brains ) , I am not very good with calculations and get different c/r on different calculation sites.
I have a highish c/r with squish at about 40 thou ( although limited due to not having much squish area on a k series head )
I am also limited to soft camshafts ( more duration on exhaust as I did go supercharge but found it slipping (( oil driven geotech ))
I wanted 0.8 bar and 7400 rpm but could not map ( dta ) above 5200 due to charger loosing boost

I am now going with a custom exhaust and remote turbo install, bigger charge cooling and intercooler (will help with pipe layout ) , water/ meth injection if required ( i believe has bennefits besides charge cooling ? )
Big question is when will I know its boost limit without it going bang ?
is there any calculation off static or dynamic c/r that can give me a max safe limit ? and could anyone be so kind to do this for me ?

bob

Edited by type49 on 5th Nov, 2011.

If I understand correctly I don't think there is possible calculation to give you what you are looking for?

When increasing boost you will then run less ign timing, this therefore is a trade off as it is the combination of boost and timing that will make power.

Every engine is different as to what timing it will stand on boost, so it is a case of a good mapper and some dyno or rolling road time to see what it will do.

Obviously you need to make sure the turbo is up to the airflow needed for the power you would like, so it is a case of doing some looking at compressor maps and sizing the turbo appropriately for your engine size, and power requirement.

thanks tom I am thinking more about boost pressure being too much I would like to go to 0.8 bar however when do we know when this is too much is there a pressure limit or designed max cr with static and added boost ?

What is your stactic CR?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

thats my problem different online calculators give me different results

Edited by type49 on 5th Nov, 2011.

Quick calc gave 10.85:1

sorry tom just checked on old notes std head is 28cc mine is 30cc
( port and polish )
I still get different results
Bowling's Compression Ratio Calculator

Input Parameters Are the Following:
Cylinder head Volume (CC) = 30.00
Piston Top Volume (CC) = 16.00
Cylinder Bore (Inches) = 3.2
Cylinder Stroke (Inches) = 3.52
Deck Height (Inches) = -0.033
Head Gasket Thickness (Inches) = 0.073
Computation Results:

Computed Compression Ratio is 9.8 to 1

use a different calculator and i get different results

80x89.3 is an 1800 k-series(rover) what liners are you using? as these may be a limiting factor above all else.

head definately 28cc? i have in my head its ~33cc will need to double check! Though this is a NON vvc head..

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

are your pistons above the deck? my calculator takes a negative number as a piston higher than the deck and positive numbers lower.
maybe thats a difference between some calculators

i get 8.7:1 with pistons below the deck and 10:1 with pistons above the deck with your data

yes its a 1.8 k series with a ms head qed banded liners

Edited by type49 on 5th Nov, 2011.

good stuff! keep us (well me lol) up to date on your build! turbo k info is very thin on the ground!

MS head? i managed to get quite a few CC's out my head by removing the squish area, another option if you know a VERY good welder, is to have the head face built up with weld and skimmed, to build a bigger chamber. (this will also sort your valve-piston issues)

with a static CR of 10:1 you may struggle to hit your desired boost, certainly unless your turbo is very efficient and well intercooled its likely to detonate. With water injection youll make it, but you have to understand if the water injection fails or runs out its byebye engine.

what are the chances of selling on the longer rods(assuming there standard dimensions?!) and having another set made? you need to get that CR down, atleast a bit! would also allow you to time the cams properly so the engine will work as intended!

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

yes I am going to run it as it is for now I guess the limit will be what the mapper can go too, however besides det its the pressure that bothers me ,I have seen split std liners on a k series
I have just got a armval duel boost with a dawes device and will have the dta controll a n75 to feed the boost in with a switch for twin boost settings ( one road one sprint / track ) , maybe better to run a duel map with the dta again will go with what the mapper is happy with

Edited by type49 on 5th Nov, 2011.

well, i can only go by my experience, ona 1600 (same bore as you know) to run 1 bar required water injection at 9.5:1 and just over a bar cracked the liners, im sure i could have run .8 on 95ron with no water/meth but it would have been close. you will jsut have to see what your tuner can do :) fingers crossed!

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

thats good info
I take it was the combined c/r and boost that cracked the liner ? water meth would only help with det ?
was it a std liner
maybe I should settle for 0.6 on such a high static cr untill rebuild then new rods I expect it should still give good results

Standard liners, liner crack was either from pressure or I ran it to 8300rpm or a mix of tge both.. You shouldn't have that issue with the qed liners so your only worry should be detonation, water meth or an over sized turbine ( keeps chamber temps down) will help! So do lairy cams ,keeps the dynamic cr down, but you don't have that option :s just get your tuner to do his v best! You'll be supprised, the k copes admirably with high cr and boost :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

detonation could crack the liner.

But I'm surprised a modern multivalve engine couldnt cope with 1 bar boost and 9.5:CR and adequately intercooled

Timing may be far from ideal, but it should still cope and run with proper mapping.

Some of the LS guys who run over 10.5:1 CR can push 10-12psi on a standard engine, ant thats a crappy old 2valve chamber.

Even some of the Honda runners pump in a lot of boost on standard CR engines.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

was just one engine, but you made me doubt myself so went over the figures and i definately needed water/meth to hit 1 bar without hearing det on the 1600. could very well have been my mapping, but the timing was pretty heavily retarded compared to the 1400 at the same(ish) CR, which took the boost with ease.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

what boost does the standard K turbo run? KKK turbo isnt it?

Garrett GT2052LS at 7psi :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

7 PSI! i could blow harder.
I like the K series. Ive worked on a few having worked in a rover garage for a few years.
I remember seeing a few CAD videos once watching how much the block flexed under certain revs.
Have you ran it without a head gasket before?

I doubt you could blow much more than 1psi.....try it and see

And if you think 7psi is bad, I just bought a Volvo 940 LPT turbo.
LPT = low pressure turbo...but even I didnt think it would be that low !! 4.5psi boost lol

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I am sorry if this topic should be in non mini ?
but as the remote turbo is now fitted with its exhaust in a tight area i have to decide on air filter set up and was thinking on my t bod k series it requires a huge filter trunking and air box
on a turbo because the driven fan is sucking the air can i get away with a smallish filter as i want to enclose it in a custom box ( same enclosed area as exhaust / turbo ) and run a smaller dia cold air feed maybe from the wheel arch or undertray , the filter would be more or less stuck on the turbo

I didnt think it was wise putting the air filter straight onto the turbo inlet due to too much hot air around and something to do with air velocity?