Ken Smith

I want to thank all of you for responding to my novice questions regarding Toyota Mini RVs. I especially want to thank and acknowledge "diesel mike" for his excellent and thorough explanation of the Toyota Diesels. Just a comment from my knowledge of Diesels in general. The IDI or indirect injection diesel in the 2 litre truck engine with it's high (24:1) compression ratio (CR) is probably no more fuel efficient than a similar gasoline engine of the same horsepower. The IDI is inefficient becasue it uses a pre-combustion chamber to ignite the mixture and requires a very high (22 - 25:1) CR to do this. A common myth is that the higher the CR, the higher the efficiency of the engine. NOT TRUE, if one looks at the literature, one finds that CRs of 16 - 18:1 are the best efficiency and most modern direct injection engines fall between these CRs. The physics of this are that beyond some point, that is somewhere between 17:1 and 18:1 CR, excess friction of having to compress air (that's 18 atmospheres of compression) to that extent overcomes the counter effectiveness of the resulting combustion. If one recalls from the terrible era of light duty IDI diesels in passenger cars, most of those cars like my 80 VW Dasher had engines that were around 1.6 liters. The output was around 48 bhp; whereas a similar 1.6 liter gasoline engine was pumping out around 85-100 bhp. So take into account that the IDI Diesel is almost 1/2 the bhp of the gasoline engine and the fact that distillate (so called Diesel fuel) has 15 to 20% more energy per gallon than gasoline (115,000 BTU per gallon for gasoline vs. 140,000 BTU per gallon for distillate) it is easy to see that the higher fuel economy of the IDI diesel is lower bhp combined with higher energy per gallon and really poor performance.

I am assisting a friend in looking at Toyota Dolphins. I have seen a few and am getting a better base of knowledge. I read "Diesel Mikes" post regarding his 1981 Diesel power RV. I assume that this is the same IDI engine that was use in all Toyota pickups and passenger cars during that era. I owned a VW IDI and it was no better quality than and did not get that much better mileage than the same size gasoline engine. Questions: 1. Were there any DI or TDI engines ever installed in Dolphins or other Toyota Mini RVs? 2. Are there any retrofit kits for DI or TDI engines available or does anyone have any experience in trying to do this? Commentary: I frankly would not advise my friend to get one of the IDI engines since they were mostly junk, inefficient and light duty not heavy duty Deisels. Any comments to that statement would be appreciated. Experience comes from toasting two 1.6 litre VW IDI engines. One lasted 90K and the second factory rebuild failed after only 5k due to a fault crankshaft. I sold it before it could do more harm to my pocket book.